42nd

Handbook

Copthorne Hotel and Resort 23-26 November Bay of Islands, ISSN 2703-4275 2020 Contents

Sponsors and exhibitors 2 Best paper awards 2 Wi-Fi access 4 General information 5 Social Events 6 Keynote speakers 8 Programme 16 Abstracts 22

2 | 42nd New Zealand Geothermal Workshop Welcome 42nd New Zealand Geothermal Workshop 2020

We are pleased to welcome delegates The New Zealand Geothermal Workshop to the 42nd New Zealand Geothermal commenced in 1979, primarily as an avenue Workshop, held at the Copthorne Hotel for graduating students of the Geothermal in the beautiful Bay of Islands. We are Institute to present their research. This thrilled that international attendees, while premise continues today, however we unfortunately unable to join us in NZ are hope the event is a forum for the entire with us online. This year’s location is a novel geothermal community to connect and one for the workshop – it provides everyone collaborate. a great chance to see Top Energy’s Ngawha We are grateful to all attendees, speakers development, and to visit the Waitangi and sponsors for their commitment to Treaty grounds which are considered the workshop in 2020. Large events in by many the birthplace of modern New the current climate involve uncertainties Zealand. beyond “business as usual” event planning. 2020 has been a year like no other – however Thank you for your support in 2020! the energy sector is an essential lifeline for New Zealand. So despite the challenges Conveners: of the COVID-19 pandemic our country’s Rosalind Archer geothermal generation continued to play a key role in providing baseload renewable David Dempsey energy to the nation. This will have required Mike O’Sullivan innovation and ingenuity from so many Sadiq Zarrouk across the sector. 2020 has also been characterised by “NZ Inc.” continuing to reach across national borders (now virtually) to support global geothermal development. We hope the workshop is a time to pause, to reflect, and to become energised about the future of geothermal in New Zealand – whether that is in direct use for process heat or other applications, or fuelling hydrogen production, or developing new resources in new areas for to propel New Zealand closer to 100% renewable electricity. What will our vehicle fleet look like by 2030? How many of you will be driving electric?

23-26 November 2020 | 1 2020 Sponsors

2020 Best Paper Awards

Ngati Tuwharetoa Geothermal Assets Ltd Best Direct Use paper

2 | 42nd New Zealand Geothermal Workshop New Zealand Geothermal Association Best New Zealand author Best student paper Best student poster

23-26 November 2020 | 3 Wi-Fi Access Please note that the venue wifi in the exhibition space is not the same network as the session rooms. Please use the below instructions to login to each space.

To login to Wi-Fi in Exhibition Space To login to Wi-Fi in Main Conference Hall (Waitaha Room): (Treaty Rooms):

• Select the network connection • Select the network connection “waitahawireless” “Copthorne Wireless”

• Type in the password: bo1wa1taha • Open your internet browser

• Connect • The Reivernet/Copthorne home page will open and it will ask you to make a selection – • Open your internet browser, this will start your choose ‘Visitors’ session • Type in the code: NZGW20

• This will then start your time

We’re steaming ahead, poised to unlock more geothermal potential - both here in Aotearoa and key locations around the globe.

www.gns.cri.nz General information The following information is provided as a guide to the Workshop. If you have any queries, please visit the registration desk.

Registration desk

For any questions, please visit the registration desk during Workshop hours.

If the registration desk is unattended, please call 027 807 9928. Workshop catering

Lunches, morning and afternoon teas will be served in the Waitaha Room. Dietary requirements

Vegetarian options are provided with each meal break. Care has been taken to ensure all Cameras and electronic recording advised dietary requirements are catered to. If you specified your dietary requirements when No personal electronic recording of We’re steaming ahead, registering, please make yourself known to the presentations is permitted in any form without poised to unlock more catering staff. the express written permission of Workshop geothermal potential - both organisers and speakers. Sessions will be here in Aotearoa and key Mobile phones recorded and available via the virtual conference locations around the globe. During all presentations please switch off or turn platform until 23 December 2020. your mobile phones to silent. Virtual Conference Platform

Presentations If you have misplaced your login details for As a courtesy to our presenters, please ensure the virtual conference platform please email you arrive at each session venue prior to the start [email protected] for assistance. of presentations. Urgent messages and lost property

Presenting authors Urgent messages for delegates and lost property Presentation slots are 15 minutes long with 3 can be directed to the registration desk. minutes scheduled for questions. Each session Messages and lost property will be held there for chair will be keeping strictly to time. collection until the conclusion of the Workshop. If you are scheduled to give a presentation, please ensure your PowerPoint is uploaded well in advance of your presentation time, preferably during the catering breaks or prior to the start of www.gns.cri.nz each day.

23-26 November 2020 | 5 Social Events There are a number of social events available to attendees. If you have not already arranged your tickets to these events, please visit the registration desk.

Welcome Reception and Powhiri Top Energy Field Trip

Monday, 23rd November, 5.30pm Friday, 27th November, 9:30am Waitangi Treaty Grounds The Top Energy Field Trip is available to those This will be a ‘drinks and nibbles’ event open who have previously registered to attend this to all registered Workshop delegates. No ticket event. required. If you aren’t sure if you have previously registered, please check with the registration desk staff.

6 | 42nd New Zealand Geothermal Workshop Duke of Marlborough Hotel, Russell

Workshop Dinner

Wednesday, 25th November 6.15pm Duke of Marlborough Hotel, Russell

Refreshing Rascals and Reprobates since 1827. Located on the waterfront of Russell in the Bay of Islands, the Duke of Marlborough Hotel offers an outstanding restaurant, accommodation and event venue. Holding New Zealand’s first liquor licence, this historical beauty has been lovingly restored and offers her visitors a great place to relax, unwind and watch the world go by.

Ferry: We will have complementary ferry service departing from the Copthorne Wharf at 6:15pm. Return service will be available at 10:30pm. Should you wish to join the dinner late or depart early you will need to purchase a trip from the public ferry providers from Paihia or Russell Wharfs.

The Workshop dinner is available to those who have previously registered to attend this event. Please make sure you present your name tag on arrival, as it includes your dinner ticket(s).

If you aren’t sure if you have previously registered, please check with the registration desk staff.

23-26 November 2020 | 7 Keynote speakers

Andrea “Andy” Blair Upflow | President of the International Geothermal Association

Andy is the President of the International Andy has experience in leading strategic Geothermal Association (Germany) and planning and tactical thinking across several co-founder of Upflow, a geothermal science, industries including governance roles that research and innovation company that builds required strategic investment decision making. expert teams to provide intelligent solutions This includes chairing the commercial arm of a to global industry. The nexus between science, Māori organisation with a significant geothermal business and community is where her expertise asset base (~$500m). sits. She has a deep understanding of the drivers A co-founder and Global Chair of Women in relating to the business of science, and a proven Geothermal (WING) (2013-2020), Andy grew ability to turn scientific ideas into economic the organisation from 83 members to over 1800 gains. members in 48 countries worldwide, making it In her previous role as Business Development the single largest geothermal association in the Manager at GNS Science (NZ) she was world. A not-for-profit organisation, WING has responsible for leading and coordinating grown into a global movement of people, both sub-surface geothermal geoscience contracts men and woman, supporting the empowerment worldwide for over 10 years. and advancement of women within the industry.

Awarded the role of Geothermal Business Andy is a Director for the Geothermal Resources Development Lead for New Zealand (2017- Association (US), Advisory Board Member for The 2020), Andy was tasked with driving commercial Rogue Bore geobrewery and Co-Chair of the investment in geothermal industrial direct Regional Skills Leadership group. use projects. The desired outcome was the development of large projects with significant positive impacts on local economies, communities, and the environment.

8 | 42nd New Zealand Geothermal Workshop Global geothermal movements: what’s happen in the world of geothermal, current focus, latest thinking, and global trends.

Andy will talk to the latest technologies, leadership role. She will provide insights into workstreams and thinking happening in regional activities, the issues and opportunities, international markets and how the International and provide some commentary on New Geothermal Association intends to play a Zealand’s role in the global future of geothermal.

Notes

23-26 November 2020 | 9 Geothermal research in Colombia: lessons learned and future perspectives. A research group focused on has been established in 2014 as an initiative between Universidad de Medellín (Colombia) and Institut national de la recherche scientifique (Québec, Canada). Seven years later the group has been awarded the Best Research Programme of the Universidad de Medellín during the X Innovation and Creativity Fair held at the end of September 2020. Daniela Blessent The research work started with the assessment of Universidad de Medellin the geothermal potential of a study area close to Professor of Environmental Engineering the Nevado del Ruiz volcano. Groundwater and heat transfer numerical modeling was used as Daniela Blessent graduated from the Politecnico a tool to simulate temperature at depth, based di Torino (Italy) in 2004 in Environmental on thermal and hydraulic measurements of rock Engineering. During her studies, she spent one properties. An hydrogeochemical study has also year (2002-2003) at the Federal Polytechnic of been started recently. The studies conducted Lausanne (Switzerland). She obtained a PhD provided new insights into the construction of in Earth Sciences in 2009, at Université Laval conceptual and numerical models for fractured (Quebec, Canada), with focus on hydrogeological geological media. numerical modeling of fractured geological media. She then worked as a professor at Perception of geothermal energy has also been Polytechnique de Montreal (Canada) from 2010 analyzed through online and face-to-face surveys to 2012. Since 2013, she has been working at the conducted in two areas of the country, in the Universidad de Medellin (Colombia) as professor Nevado del Ruiz and Azufral volcanoes. Feasibility in the Environmental Engineering department. of shallow geothermal energy installations have Her research activities currently benefit from also started to be investigated. multiple international collaborations, in particular The performed activities allowed the creation of thanks to the international project IGCP636 a solid research network, fostering participation “Geothermal resources for energy transition”, in geosciences of young researchers, students, which is part of the UNESCO International and women. The extensive participation of Geoscience Programme. Since January 2020, she scientists from several countries, the enrollment is the president of the Colombian Geothermal of undergraduate and graduate students, and Association (AGEOCOL). the numerous outcomes highlight the key role of international collaboration and visibility for Colombia, where geothermal development is at its beginning.

10 | 42nd New Zealand Geothermal Workshop To support the development of the geothermal and engineering academic programs, since industry in Colombia, it is important to promote the geothermal field is multidisciplinary and outreach activities and to include courses it requires a proper communication among on geothermal energy in both geoscience different disciplines, including social sciences.

Notes

23-26 November 2020 | 11 Ngawha Geothermal Field Development Russell Shaw, Chief Executive of Top Energy Group will present a paper detailing the development of the geothermal field at Ngawha from the early Ministry of Works developments through to the present day.

The paper will particularly focus on the most recent developments with the commissioning of the 15MW OEC3 in 2008 and the planned commissioning of the 32MW OEC4 in November 2020. Recent field modelling techniques will be Russell Shaw reviewed as will well testing results. There will TOP ENERGY GROUP also be a discussion on the Non Condensable Chief Executive Gasses (including CO2) which occur in the field As an electrical engineer with over 25 years’ and how these have changed over the past 20 experience in the utility sector, Russell years of geothermal generation. has significant experience in strategy, management, risk and operations with extensive knowledge of asset management, performance improvement and engineering. Prior to joining Top Energy in 2008, Russell was General Manager for Operations at WEL Networks where he led WEL’s Asset Management, Procurement and Field Services groups of over 150 staff. Prior to this Russell was a partner with UMS Group, a global utility management consulting group. Russell is a Chartered Electrical Engineer, has an honours degree in Electrical and Electronic Engineering, an MSc in Engineering Business Management and is a Fellow of the Institute of Engineering and Technology and Engineering NZ. He is also a member of the NZ Institute of Directors.

12 | 42nd New Zealand Geothermal Workshop Notes

23-26 November 2020 | 13 The Future of Hydrogen for NZ

Linda Wright Chief Executive, New Zealand Hydrogen Association

Throughout her 20-year career Linda has been at the forefront of driving innovation and change across the sustainability, solid waste and renewable energy sectors.

Linda has an extensive global network across the hydrogen value chain and understands intimately the value proposition for renewable hydrogen, and in New Zealand in particular. In 2016 Linda founded a private sector consortium to progress the delivery of hydrogen infrastructure, which supported by the Government, transitioned to become the New Zealand Hydrogen Association in 2018. Linda is the Chief Executive of the Association and is committed to delivering its objectives of facilitating the delivery of hydrogen solutions both domestically and for export.

Linda has been involved in progressing technical aspects of hydrogen production, storage, demand and end-use scenarios and she is currently developing strategic alliances with private sector entities to deliver a range of hydrogen projects across New Zealand. She is also engaged with international partners to advance the role that

hydrogen can play in the transition to a low emission future and to position New Zealand at the forefront of the global hydrogen economy.

14 | 42nd New Zealand Geothermal Workshop Notes

23-26 November 2020 | 15 - - Session 1.3. -Geoscience 1 Room Rangitira 105 | INVESTING IN EXPLORATION GEOSCIENCE AND INNOVATION. GEOSCIENCE AND INNOVATION. 105 | INVESTING IN EXPLORATION FOR TOOL RESOURCE PRIORITISATION A GIS-BASED GEOTHERMAL – Bignall REGION, JAPAN TOHOKU 42 | A REVIEW OF THE HYDROGEOLOGY OF THE TAUHARA DOMES TAUHARA THE OF THE HYDROGEOLOGY 42 | A REVIEW OF TIC BORES, TAUPŌ, NEW ZEALAND – Lebe TAUPŌ, TIC BORES, 9 | THREE NEW HOT SPRING VENTS EXPOSED AT ORAKEI KORAKO ORAKEI KORAKO EXPOSED AT VENTS SPRING THREE NEW HOT 9 | NEW ZEALAND – Lynne FIELD, GEOTHERMAL 25 | IMAGING FEEDZONE DIVERSITY. CASE STUDIES FROM SUMA DIVERSITY. FEEDZONE 25 | IMAGING NEW ZEALAND ZONE, VOLCANIC TAUPŌ THE TRA, INDONESIA AND – Wallis 50 | BLACK TERRACE, ROTOMAHANA – White – ROTOMAHANA TERRACE, 50 | BLACK 142 | CONCEPTUAL MODEL EVOLUTION OF THE TAUHARA TAUHARA THE OF MODEL EVOLUTION 142 | CONCEPTUAL RESERVOIR FROM 1960-2020 – Sepulveda GEOTHERMAL 138 | GEOLOGICAL MODEL & PERMEABILITY FRAMEWORK138 | GEOLOGICAL OF BUKIT INDONESIA – Ikhwan FIELD, GEOTHERMAL DAUN PRESENTATION) ( INTERNATIONAL -

Session 1.2. Reservoir 1 Engineering Room 2 Treaty 28 | SWANHILD. NUMERICAL PRESSURE TRANSIENT ANALYSIS TRANSIENT ANALYSIS NUMERICAL PRESSURE 28 | SWANHILD. RESERVOIR SIMULATION VOLSUNG GEOTHERMAL THE USING PACKAGE – Mclean - IN GEOTHER OF UNKNOWN PARAMETERS 116 | REPRESENTATION – Nicholson MODEL CALIBRATION MAL 123 | THE ROLE OF THERMAL STRESS IN ENHANCING THE RESER - STRESS IN ENHANCING THERMAL THE ROLE OF 123 | – Aliyu SYSTEMS VOIR PROPERTIES OF ENHANCED GEOTHERMAL 12 | AN UPDATED COMPUTER MODEL OF ROTORUA GEOTHERMAL GEOTHERMAL MODEL OF ROTORUA COMPUTER 12 | AN UPDATED FIELD – Dekkers EL USING EXPERIMENTAL DESIGN (ED) AND RESPONSE SURFACE AND RESPONSE SURFACE DESIGN (ED) EL USING EXPERIMENTAL (RSM) – Ciriaco METHODOLOGY 140 | ESTIMATING ’S 50 YEARS AND 100 YEARS MWE YEARS AND 100 YEARS 50 WAIRAKEI’S 140 | ESTIMATING MOD STATE NATURAL FROM A CALIBRATED CAPACITY POTENTIAL 124 | A NEW NUMERICAL MODEL OF THERMAL APERTURE CHANG - THERMAL 124 | A NEW NUMERICAL MODEL OF RESERVOIR SYSTEM – Aliyu ES IN AN ENHANCED GEOTHERMAL 43 | PATCHING HELE-SHAW CELLS TO SIMULATE SILICA SCALE SIMULATE TO CELLS HELE-SHAW 43 | PATCHING DEPOSITION IN DISCRETE FRACTURE NETWORKS – Aghajannezhad Registration Open Registration Grounds Treaty Waitangi | Reception Welcome Open Registration Housekeeping and Opening Welcome TRENDS THINKING, AND GLOBAL CURRENT FOCUS, LATEST OF GEOTHERMAL, WORLD THE HAPPEN IN WHAT’S MOVEMENTS. GEOTHERMAL GLOBAL Blair “Andy” Speaker | Andrea Keynote Morning Tea Session 1.1. Environmental Room 1 Treaty 51 | ENVIRONMENTAL BASELINE SURVEY FOR GEOTHERMAL BASELINE SURVEY FOR GEOTHERMAL 51 | ENVIRONMENTAL PROSPECT IN UGANDA KIBIRO GEOTHERMAL AT DEVELOPMENT – Ouma PRESENTATION) (INTERNATIONAL 80 | ECOLOGICAL INFORMATION FOR GEOTHERMAL SITES IN FOR GEOTHERMAL INFORMATION 80 | ECOLOGICAL REGION – Beadel 37 | CHANGING RESOURCE MANAGEMENT OF SURFACE WATER WATER OF SURFACE 37 | CHANGING RESOURCE MANAGEMENT – Collins DRILLING DEMANDS MEET GEOTHERMAL TO ALLOCATION 47 | SINTER-FORMING SPRINGS AND GEYSERS OF THE WAIKATO WAIKATO THE OF 47 | SINTER-FORMING SPRINGS AND GEYSERS REGION – Luketina 44 | GREENHOUSE GAS EMISSIONS FROM NEW ZEALAND AND INDUSTRIAL DIRECT USE POWER GENERATION GEOTHERMAL. – Mclean UPDATE | INDUSTRY NTGA EASTLANDS | INDUSTRY UPDATE UPDATE EASTLANDS | INDUSTRY Monday 23 November Monday 3.00 5.30- 7.00 24 November Tuesday 8.00 8.30 8.45 9.00 9.45 10.15 10.30 10.45 11.00 11.15 11.30 11.45 42nd New Zealand Geothermal Workshop Geothermal Zealand 42nd New 16 - - Session 2 2.3. Geoscience Room Rangitira 83 | B-VALUE MAPPING FOR VOLCANIC-RELATED GEOTHERMAL GEOTHERMAL VOLCANIC-RELATED FOR MAPPING 83 | B-VALUE CO VOLCANO, DEL RUIZ FOR NEVADO A CASE STUDY SYSTEM. LOMBIA – Bustos 139 | A CONCEPTUAL APPROACH TO “3-D PLAY FAIRWAY” ANALYSIS ANALYSIS FAIRWAY” “3-D PLAY TO APPROACH 139 | A CONCEPTUAL – O’Brien AND DEVELOPMENT EXPLORATION FOR GEOTHERMAL 63 | RATIONALE FOR SCIENTIFIC DRILLING AT THE OKATAINA VOL THE OKATAINA FOR SCIENTIFIC DRILLING AT 63 | RATIONALE INTERACTIONS BETWEENCANIC CENTRE: EXPLORING AN ACTIVE – Massiot AND MICROBIOTA CIRCULATION FLUID CALDERA, RIFT, Session 3.3 - Room Rangitira SEEQUENT | INDUSTRY UPDATE SEEQUENT | INDUSTRY JACOBS | INDUSTRY UPDATE | INDUSTRY JACOBS TN2T | INDUSTRY UPDATE TN2T | INDUSTRY DOBBIE | INDUSTRY UPDATE DOBBIE | INDUSTRY - Session 2.2. Culture and Community Session 2.2. Culture Room 2 Treaty 66 | A HOLISTIC AND CULTURALLY RESPONSIVE APPROACH TO TO RESPONSIVE APPROACH 66 | A HOLISTIC AND CULTURALLY – AND MANAGEMENT PLANNING, MONITORING GEOTHERMAL Clubb 130 | HE PUNA I RAWEKE, HE PUNA WHAKATŌTŌ – Severne WHAKATŌTŌ HE PUNA 130 | HE PUNA I RAWEKE, TO REGIONAL COUNCIL. EMBRACING CHANGE, COLLABORATION, COLLABORATION, CHANGE, EMBRACING REGIONAL COUNCIL. TO – Luketina AND INNOVATION 48 | TWENTY-FIVE YEARS OF GEOTHERMAL MONITORING BY WAIKA BY MONITORING OF GEOTHERMAL YEARS TWENTY-FIVE 48 | 128 | TE AHI TIPUA KI TĀHORAKURI A130. ESTABLISHING AN A130. ESTABLISHING TĀHORAKURI KI TIPUA TE AHI 128 | & HAPŪ IN WHANAU PLAN FOR DEVELOPMENT ECONOMIC – Kora ENVIRONMENTS DEGRADED GEOTHERMAL Session 3.2. Reservoir 2 Engineering Room 2 Treaty 117 | OPTIMAL DATA COLLECTION AND DATA-WORTH-ANALYSIS COLLECTION AND DATA-WORTH-ANALYSIS DATA 117 | OPTIMAL – Nicholson MODEL CALIBRATION FOR GEOTHERMAL - GEOTHER MODEL OF MONTSERRAT COMPUTER 6 | AN UPDATED FIELD – O’Sullivan MAL 11 | DEVELOPMENT OF A TRANSIENT, MULTI-FEED GEOTHERMAL GEOTHERMAL MULTI-FEED TRANSIENT, OF A 11 | DEVELOPMENT Tonkin – WELLBORE SIMULATOR 10 | ON THE CHOICE OF PRIMARY VARIABLES IN TRANSIENT IN VARIABLES THE CHOICE OF PRIMARY 10 | ON Tonkin WELLBORE MODELLING – GEOTHERMAL Lunch and Poster Session. and Poster Lunch RESOURCE USE – Kissick GEOTHERMAL AND PLANNING FRAMEWORK FOR CONVENTIONAL 18 | NEW ZEALAND’S REGULATORY Twesigye – IN UGANDA SYSTEMS GEOTHERMAL OF EXTENSIONAL–TYPE 20 | GEOCHEMISTRY BUSINESS – Imamura OPPORTUNITIES AND ITS FOR NEW ZEALAND’S GEOTHERMAL IN JAPAN POWER PLANTS GEOTHERMAL 23 | A REVIEW OF SMALL–SCALE – Xicara GUATEMALA SYSTEM, GEOTHERMAL 31 | A NEW NUMERICAL MODEL OF AMATITLAN – Lebe WAIOTAPU AND WAIKITE, MOKAI, NGATAMARIKI, ATIAMURI, ZONE. VOLCANIC TAUPO THE FIELDS IN OF FIVE GEOTHERMAL STUDY GEOCHEMISTRY WATER 40 | A COMPARATIVE – Duque TUBING SYSTEMS ANTI–SCALANT IN GEOTHERMAL 75 | USE OF ICE PLUGS INDONESIA – Nusantara FIELD, GEOTHERMAL MODEL. HULULAIS FACIES STRATOVOLCANO TO IMPLICATION AND ITS ROCK FORMATION SUBSURFACE OF HULULAIS 121 | CHARACTERIZATION INDONESIA – Nurseto BENGKULU, SYSTEM, NETWORK GEOTHERMAL OF HULULAIS FAULT 126 | GEOLOGY INDONESIA – Pratama BENGKULU, FIELD, GEOTHERMAL OF HULULAIS VOLCANOSTRATIGRAPHY 127 | AGM NZGA UPDATE | INDUSTRY NZGA UPDATE | INDUSTRY MB CENTURY Session 2.1 Room 1 Treaty WESTERN ENERGY | INDUSTRY UPDATE WESTERN ENERGY | INDUSTRY | INDUSTYMERCURY UPDATE WING | INDUSTRY UPDATE WING | INDUSTRY GOETHERMAL UPDATE NEW ZEALAND | INDUSTRY Afternoon Tea Afternoon 1 Technology Ground Session 3.1. Above Room 1 Treaty 27 | GEOTHERMAL STEAM TURBINE DEPOSITION FUNDAMENTALS TURBINE DEPOSITION FUNDAMENTALS STEAM 27 | GEOTHERMAL – Addison 26 | NGATI TUWHARETOA GEOTHERMAL ASSETS LTD REBOILER ASSETS LTD GEOTHERMAL TUWHARETOA 26 | NGATI RESOLVE TO IMPROVEMENTS CHEMISTRY WATER/STEAM PLANT ISSUES – Addison ONGOING CORROSION - IN GEOTHER REPLACEMENT SYSTEM EXCITATION 56 | GENERATOR – Paloso AND PITFALLS – MERITS POWER STATIONS MAL 97 | DEI, DOUBLE ENERGY INPUT. A NOVEL MODEL FOR ELECTRICI- 97 | DEI, DOUBLE ENERGY INPUT. – Ramirez TY GENERATION Tuesday 24 November (continued) 24 November Tuesday 12.00- 1.30 1.00 1.30 1.45 2.00 2.15 2.30 2.45 3.00 3.15 3.45 4.00 4.15 4.30

17 Session 4.3 Room Rangitira WORKSAFE | INDUSTRY UPDATE WORKSAFE | INDUSTRY ARA AKE | INDUSRTY UPDATE SCHLUMBERGER | INDUSTRY UPDATE | INDUSTRY SCHLUMBERGER SUEZ IXOM | INDUSTRY UPDATE | INDUSTRY SUEZ IXOM NALCO | INDUSTRY UPDATE | INDUSTRY NALCO THORNDON COOK | INDUSTRY UPDATE | INDUSTRY THORNDON COOK SOLENIS | INDUSTRY UPDATE SOLENIS | INDUSTRY Session 5.3 Room Rangitira 19 | NEW ZEALAND’S SUPERCRITICAL OPPORTUNITY. MOVING 19 | NEW ZEALAND’S SUPERCRITICAL OPPORTUNITY. – Blair TECHNOLOGY DEPLOYED TO RESOURCE FROM POTENTIAL GEOTHERMAL NEXT GENERATION WORKSHOP NEXT GENERATION GEOTHERMAL Session 4.2. Direct Use / Culture and Community Session / Culture 4.2. Direct Use Room 2 Treaty - GEOTHER ASSESSMENT OF ROTORUA LOSS HEAT 134 | SURFACE NEW ZEALAND – Seward FIELD, MAL 16 | GEOHEAT STRATEGY FOR AOTEAROA N.Z. – 2020 PROGRESS FOR AOTEAROA STRATEGY 16 | GEOHEAT – Carey UPDATE 17 | OPTIMAL SETTINGS17 | OPTIMAL USE I FOR DIRECT GEOTHERMAL WITH NUMERICAL MODELLING – Pearson-Grant NVESTIGATED 14 | CAN THE REYKJAVÍK DISTRICT HEATING SYSTEM (DHS) BE USED SYSTEM DISTRICTTHE REYKJAVÍK HEATING 14 | CAN STUDY DHS? A COMPARATIVE AS A MODEL FOR ROTORUA – Zuquim 32 | COMMUNITY ENGAGEMENT IN GEOTHERMAL DEVELOPMENT DEVELOPMENT IN GEOTHERMAL 32 | COMMUNITY ENGAGEMENT PROSPECT – OF KIBIRO GEOTHERMAL CASE STUDY IN UGANDA. Aijuka PRESENTATION) (INTERNATIONAL 24 | GENDER MAINSTREAMING IN THE DEVELOPMENT OF DIENG THE DEVELOPMENT IN 24 | GENDER MAINSTREAMING Yogandari INDONESIA – FIELD, GEOTHERMAL AND PATUHA PRESENTATION) ( INTERNATIONAL Session 5.2. Above Ground Technology 3 Technology Ground Session 5.2. Above Room 2 Treaty 129 | MICROBIALLY INDUCED DEGRADATION OF FIBRE REINFORCED INDUCED DEGRADATION 129 | MICROBIALLY POWER OF A GEOTHERMAL TOWER THE COOLING PLASTIC (FRP) IN – Clark STATION 76 | INTEGRATION OF THE CALCIUM SILICATE (CASIL) TECHNOLOGY TECHNOLOGY (CASIL) SILICATE THE CALCIUM OF 76 | INTEGRATION PREVENT SILICA TO POWER GENERATION GEOTHERMAL INTO – Johnston AN UPDATE DEPOSITION, AND CASIL APPLICATIONS. 131 | CFD MODELLING OF CORROSION TEST LOOPS FOR TEST LOOPS 131 | CFD MODELLING OF CORROSION – Lichti APPLICATIONS FLUID GEOTHERMAL 103 | GEOTHERMAL STEAM PURITY MODELLING – THEORY AND THEORY PURITY STEAM MODELLING – 103 | GEOTHERMAL PRACTICE – Mills - - Housekeeping Housekeeping LESSONS LEARNED AND FUTURE PERSPECTIVES RESEARCH IN COLOMBIA. GEOTHERMAL PRESENTATION) (INTERNATIONAL | Daniela Blessent Speaker Keynote UPDATE GNS | INDUSTRY Morning Tea 2 Technology Ground Session 4.1. Above Room 1 Treaty 90 | INJECTIVITY CHANGES AT NGATAMARIKI – Potter NGATAMARIKI 90 | INJECTIVITY CHANGES AT 64 | SUCCESSFUL TURBINE GENERATOR OUTAGE EXECUTION – Krige OUTAGE TURBINE GENERATOR 64 | SUCCESSFUL 62 | DIGITAL TWINS FOR THE GEOTHERMAL INDUSTRY. THEORY AND THEORY INDUSTRY. THE GEOTHERMAL TWINS FOR 62 | DIGITAL PRACTICE – Young 67 | POIHIPI COOLING WATER SYSTEM - TAKING A HOLISTIC TAKING - SYSTEM WATER 67 | POIHIPI COOLING PROBLEMS AND IMPLEMENTING INVESTIGATING TO APPROACH SOLUTIONS – Young 15 | PENTANE EVACUATION FOR BINARY PLANTS – Mclellan PLANTS FOR BINARY EVACUATION 15 | PENTANE 81 | WELL PERFORMANCE DIAGNOSTICS AND FORECASTING USING DIAGNOSTICS WELL PERFORMANCE 81 | FROM – A CASE STUDY WELLBORE SIMULATOR THE GUDRUN NEW ZEALAND – Quinao KAWERAU, Lunch FIELD DEVELOPMENT GEOTHERMAL NGAWHA | Russell Shaw Speaker Keynote UPDATE ENERGY | INDUSTRY CONTACT Session 5.1. Drilling Room 1 Treaty PRODUCTION FLUID DEBRIS IN GEOTHERMAL 71 | MANAGING Diaz – Rivera 13 | ACCURATE LOCATION OF FEED ZONES. ASSESSING OBSCURA OF FEED ZONES. LOCATION 13 | ACCURATE TION BY THE LINER IN GEOTHERMAL WELLS – Goble THE LINER IN GEOTHERMAL TION BY 35 | CUSTOM PDC BITS SIGNIFICANTLY INCREASE DRILLING SIGNIFICANTLY PDC BITS 35 | CUSTOM DRILLING PROJECT – GEOTHERMAL TAUHARA IN PERFORMANCE Lock 3 | USING AIR-CAP TESTING TO MONITOR AND MEASURE MONITOR TO TESTING 3 | USING AIR-CAP Winmill WELL CASING INTEGRITY – GEOTHERMAL 106 | STUCK PIPE FREEING PROBABILITY IN GEO OF SUCCESS THERMAL DRILLING OPERATION. A CASE STUDY IN WEST JAVA WEST JAVA IN A CASE STUDY DRILLING OPERATION. THERMAL – Alamsyah PRESENTATION) (INTERNATIONAL Wednesday 25 November Wednesday 8.45 9.00 9.45 10.00 10.30 10.45 11.00 11.15 11.30 11.45 12.15 1.15 2.15 12.00 2.15 2.30 2.45 3.00 3.15

18 101 | SIMULATING INTERFERENCE EFFECT IN THE REINJECTION INTERFERENCE EFFECT IN 101 | SIMULATING WELLS – Marastio PRESENTATION) ( INTERNATIONAL Session 6.3 - Geochemistry Room Rangitira OF SUPERCRITICAL CAR- AND SEQUESTRATION 94 | UTILISATION Tosha FIELD – THE GEOTHERMAL IN BON DIOXIDE PRESENTATION) (INTERNATIONAL 136 | TURBULENCE MEDIATED RAPID ALUMUINOSILICATE RAPID ALUMUINOSILICATE TURBULENCE MEDIATED 136 | NGATAMARIKI VEIN BRECCIA. IN HYDROTHERMAL FORMATION NEW ZEALAND – Newton POWERSTATION, GEOTHERMAL ON OF EGS APPLICATION THE PROVISIONAL RESULTS 86 | Yoshimatsu – POWER PLANT IN JAPAN GEOTHERMAL PRESENTATION) (INTERNATIONAL 8 | A PRACTICAL APPLICATION OF CHLORIDE MASS BALANCE MASS OF CHLORIDE 8 | A PRACTICAL APPLICATION STEAM OF A GEOTHERMAL THE EVALUATION TO METHOD IN INDONESIA – Dong SYSTEM GENERATION THE TO AND OIL PRICE DROP’S104 | COVID-19 IMPACTS DRILLING PROJECT IN INDONESIA – Fininda GEOTHERMAL PRESENTATION) (INTERNATIONAL 21 | EXPERIMENTAL DETERMINATION OF RATE CONSTANTS FOR THE FOR CONSTANTS OF RATE DETERMINATION 21 | EXPERIMENTAL 2-NSA, 2,6-NDS, 2,7-NDS, 1,5-NDS TRACERS THE BREAKDOWN OF – Sajkowski CONDITIONS AND 1,6-NDS UNDER GEOTHERMAL 52 | CO2 DISCHARGE FROM LAKE ROTOITI, NEW ZEALAND – Yang NEW ZEALAND – DISCHARGE FROM LAKE ROTOITI, 52 | CO2 70 | INVESTIGATION AND APPLICATION OF FLASHING FLOW NOZ- OF FLASHING FLOW AND APPLICATION 70 | INVESTIGATION TE TURBINE LIFE REDUCTION AT GEOTHERMAL MITIGATE TO ZLES – Misa MIHI STATION 96 | SIMULATING EFFECT OF INSULATED DRILLPIPE ON DOWNHOLE EFFECT OF INSULATED 96 | SIMULATING WELL DRILLING IN SUPERCRITICAL GEOTHERMAL TEMPERATURE – Ando PRESENTATION) ( INTERNATIONAL Session 6.2 - Future Technologies and Projects Technologies Session 6.2 - Future Room 2 Treaty EXPANDABLE METAL SOLUTIONS COMPLETION WELLTEC 99 | WELL CEMENTING FOR GEOTHERMAL AND 2ND STAGE PACKER RE-LINING EDC PHILIPPINES – Jamieson PRESENTATION) ( INTERNATIONAL 137 | A ROBUST SUPERCRITICAL GEOTHERMAL SIMULATOR SIMULATOR 137 | A ROBUST SUPERCRITICAL GEOTHERMAL – O’Sullivan SELECTION98 | DRILL BITS PROCUREMENT IN NON-CONSIGNMENT DRILLING PROJECTARRANGEMENT IN GEOTHERMAL – Kusumawardani PRESENTATION) ( INTERNATIONAL 5 | FUTURE GEOTHERMAL GENERATION STACK. FACTORS FACTORS STACK. GENERATION 5 | FUTURE GEOTHERMAL 2060 TO PROJECTS IN NZ NEW GEOTHERMAL INFLUENCING – Lawless WELL INTERVENTION AND ENHANCEMENT IN DIENG 84 | FIELDS, INDONESIA – Elfajrie GEOTHERMAL PRESENTATION) (INTERNATIONAL 141 | BUOYANCY VORTEX POWER FROM LOW-TEMPERATURE HEAT. HEAT. VORTEX POWER FROM LOW-TEMPERATURE 141 | BUOYANCY PROGRESS – Hawkes 89 | GEOTHERMAL DEVELOPMENT. A GAME OF CHANCE AND WIT OF CHANCE AND A GAME DEVELOPMENT. 89 | GEOTHERMAL – Potter 111 | CHALLENGES IN PROVIDING A RELIABLE WATER DISTRIBUTION WATER 111 | CHALLENGES IN PROVIDING A RELIABLE IN INDONESIA DRILLING OPERATION FOR GEOTHERMAL SYSTEM – Adityatama PRESENTATION) (INTERNATIONAL Wright | Linda Speaker Keynote Morning Tea Afternoon Tea Afternoon Session 6.1 Room 1 Treaty NZTE | INDUSTRY UPDATE UPDATE NZTE | INDUSTRY PRESENTATION) (INTERNATIONAL NZTE | INDUSTRY UPDATE UPDATE NZTE | INDUSTRY PRESENTATION) (INTERNATIONAL NZTE | INDUSTRY UPDATE UPDATE NZTE | INDUSTRY PRESENTATION) (INTERNATIONAL NZTE | INDUSTRY UPDATE UPDATE NZTE | INDUSTRY PRESENTATION) (INTERNATIONAL The Duke of Marlborough Hotel | Russell Hotel of Marlborough Duke The Wednesday 25 November (continued) 25 November Wednesday 3.30 26 November Thursday 8.459.00 Housekeeping IN NZ THE FUTURE FOR HYDROGEN 9.45 10.15 UPDATE INSTITUTE | INDUSTRY GEOTHERMAL 3.45 10.30 UPDATE | INDUSTRY REGIONAL COUNCIL WAIKATO 4.15 10.45 UPDATE | INDUSTRY OF PLENTY REGIONAL COUNCIL BAY 4.30 11.00 | INDUSTRYUPDATE WHAKAREWAREWA 4.45 5.00 6.15Wharf7.00 Copthorne from | via Ferry Venue Dinner to Travel 10.30 Dinner Conference NZGW

19 87 | OPPORTUNITIES FOR ELECTRICITY GENERATION WITH BINARY WITH BINARY 87 | OPPORTUNITIES FOR ELECTRICITY GENERATION AREA BALAI GEOTHERMAL IN LUMUT POWER PLANTS CYCLE – Gunawan PRESENTATION) (INTERNATIONAL 29 | HYDROGEOCHEMICAL CHARACTERISTICS OF GEOTHERMAL CHARACTERISTICS29 | HYDROGEOCHEMICAL OF GEOTHERMAL INDONESIA – Sahdarani IN MOUNT LAWU, WATER PRESENTATION) (INTERNATIONAL 34 | COMMON PRACTICE OF FORMATION EVALUATION PROGRAM EVALUATION PRACTICE OF FORMATION 34 | COMMON DRILLING IN GEOTHERMAL – Chandra PRESENTATION) ( INTERNATIONAL OPPORTUNITY59 | PRE INDEPENDENT AFRICA. FOR A LOST – Bacwa RESOURCE DEVELOPMENT GEOTHERMAL PRESENTATION) (INTERNATIONAL Session 8.3 Room Rangitira 122 | FEEDZONE EVALUATION IN HULULAIS GEOTHERMAL FIELD, FIELD, GEOTHERMAL IN HULULAIS EVALUATION 122 | FEEDZONE INDONESIA – Arifin BENGKULU, PRESENTATION) (INTERNATIONAL 92 | DRILLING ACTIVITIES AND PARAMETERS ANALYSIS TO OPTIMIZE TO ANALYSIS 92 | DRILLING ACTIVITIES AND PARAMETERS Yuswandari FIELD – STUCK PIPE PREVENTION IN A GEOTHERMAL PRESENTATION) (INTERNATIONAL 91 | NON-PRODUCTIVE TIME ANALYSIS FROM GEOTHERMAL FROM GEOTHERMAL TIME ANALYSIS 91 | NON-PRODUCTIVE IMPROVE FUTURE DRILLING TO WEST JAVA IN DRILLING CAMPAIGN PLANNING – Rachmadani PRESENTATION) (INTERNATIONAL - 88 | SIGNIFICANCE AND METHODOLOGY OF GEOTHERMAL RE - OF GEOTHERMAL 88 | SIGNIFICANCE AND METHODOLOGY Tano – SURVEY IN JAPAN SOURCE POTENTIAL PRESENTATION) (INTERNATIONAL 85 | HYDROTHERMAL ALTERATION AND FLUID CHARACTERISTIC AND FLUID ALTERATION 85 | HYDROTHERMAL REGENCY, PASAMAN FIELD, GEOTHERMAL OF PANTI STUDY Wibisono INDONESIA – WEST SUMATRA, PRESENTATION) (INTERNATIONAL 30 | SIGNIFICANCE OF PRESSURE LET DOWN STATION IN MITIGAT 30 | SIGNIFICANCE OF PRESSURE LET DOWN STATION ING EFFECTS OF SILICA PRECIPITATION IN STEAM PIPELINES. IN STEAM ING EFFECTS OF SILICA PRECIPITATION OF OLKARIA – Chumari A CASE STUDY PRESENTATION) (INTERNATIONAL 55 | GEOLOGY OF EXTENSIONAL-TYPE GEOTHERMAL SYSTEMS IN SYSTEMS GEOTHERMAL OF EXTENSIONAL-TYPE 55 | GEOLOGY – Rusoke UGANDA PRESENTATION) (INTERNATIONAL Session 8.2 Room 2 Treaty 107 | DISCRETE VS INTEGRATED PROJECT MANAGEMENT (IPM) AND PROJECT (IPM) MANAGEMENT VS INTEGRATED 107 | DISCRETE - DRILLING SERVICE FOR GEOTHER (IDS) CONTRACT INTEGRATED DRILLING IN INDONESIA – Agustino MAL PRESENTATION) (INTERNATIONAL 4 | FUTURE SUCCESS LOW TEMPERATURE MICRO GEOTHERMAL MICRO GEOTHERMAL TEMPERATURE LOW 4 | FUTURE SUCCESS – Knight POWER GENERATION PRESENTATION) (INTERNATIONAL 57 | COMPARISON OF WELLHEAD COMPLETION DESIGNS FOR WELLHEAD COMPLETION OF 57 | COMPARISON SPOOL AND IN INDONESIA. EXPANSION OPERATIONS GEOTHERMAL IN INDONESIA – Putri CASING HEAD COMPLETIONS PRESENTATION) (INTERNATIONAL 22 | CONCEPTUAL MODEL OF OUTFLOW ZONE IN MOUNT UNG - ZONE MODEL OF OUTFLOW 22 | CONCEPTUAL USING CENTRAL JAVA SEMARANG, SYSTEM, ARAN GEOTHERMAL ANALYSIS OF MANIFESTATION AND GEOCHEMISTRY GEOLOGY – Kencana PRESENTATION) (INTERNATIONAL HALLIBURTON | INDUSTRY UPDATE | INDUSTRY HALLIBURTON DEMETER | INDUSTRY UPDATE DEMETER | INDUSTRY UPFLOW | INDUSTRY UPDATE | INDUSTRY UPFLOW Lunch Industry Panel Session 8.1 Room 1 Treaty BASELOAD CAPITAL | INDUSTRY UPDATE | INDUSTRY CAPITAL BASELOAD MTL | INDUSTRY UPDATE | INDUSTRY MTL PUKEORA LAKEFRONT HOLDINGS | INDUSTRY UPDATE PUKEORA LAKEFRONT HOLDINGS | INDUSTRY Workshop close and awards Workshop Thursday 26 November (continued) 26 November Thursday 11.15 11.30 11.45 12.00 12.15 1.15- 2.15 2.15- 2.30 2.30 2.45 3.00 3.15

20 | 42nd New Zealand Geothermal Workshop 87 | OPPORTUNITIES FOR ELECTRICITY GENERATION WITH BINARY WITH BINARY 87 | OPPORTUNITIES FOR ELECTRICITY GENERATION AREA BALAI GEOTHERMAL IN LUMUT POWER PLANTS CYCLE – Gunawan PRESENTATION) (INTERNATIONAL 29 | HYDROGEOCHEMICAL CHARACTERISTICS OF GEOTHERMAL CHARACTERISTICS29 | HYDROGEOCHEMICAL OF GEOTHERMAL INDONESIA – Sahdarani IN MOUNT LAWU, WATER PRESENTATION) (INTERNATIONAL 34 | COMMON PRACTICE OF FORMATION EVALUATION PROGRAM EVALUATION PRACTICE OF FORMATION 34 | COMMON DRILLING IN GEOTHERMAL – Chandra PRESENTATION) ( INTERNATIONAL OPPORTUNITY59 | PRE INDEPENDENT AFRICA. FOR A LOST – Bacwa RESOURCE DEVELOPMENT GEOTHERMAL PRESENTATION) (INTERNATIONAL Session 8.3 Room Rangitira 122 | FEEDZONE EVALUATION IN HULULAIS GEOTHERMAL FIELD, FIELD, GEOTHERMAL IN HULULAIS EVALUATION 122 | FEEDZONE INDONESIA – Arifin BENGKULU, PRESENTATION) (INTERNATIONAL 92 | DRILLING ACTIVITIES AND PARAMETERS ANALYSIS TO OPTIMIZE TO ANALYSIS 92 | DRILLING ACTIVITIES AND PARAMETERS Yuswandari FIELD – STUCK PIPE PREVENTION IN A GEOTHERMAL PRESENTATION) (INTERNATIONAL 91 | NON-PRODUCTIVE TIME ANALYSIS FROM GEOTHERMAL FROM GEOTHERMAL TIME ANALYSIS 91 | NON-PRODUCTIVE IMPROVE FUTURE DRILLING TO WEST JAVA IN DRILLING CAMPAIGN PLANNING – Rachmadani PRESENTATION) (INTERNATIONAL - 88 | SIGNIFICANCE AND METHODOLOGY OF GEOTHERMAL RE - OF GEOTHERMAL 88 | SIGNIFICANCE AND METHODOLOGY Tano – SURVEY IN JAPAN SOURCE POTENTIAL PRESENTATION) (INTERNATIONAL 85 | HYDROTHERMAL ALTERATION AND FLUID CHARACTERISTIC AND FLUID ALTERATION 85 | HYDROTHERMAL REGENCY, PASAMAN FIELD, GEOTHERMAL OF PANTI STUDY Wibisono INDONESIA – WEST SUMATRA, PRESENTATION) (INTERNATIONAL 30 | SIGNIFICANCE OF PRESSURE LET DOWN STATION IN MITIGAT 30 | SIGNIFICANCE OF PRESSURE LET DOWN STATION ING EFFECTS OF SILICA PRECIPITATION IN STEAM PIPELINES. IN STEAM ING EFFECTS OF SILICA PRECIPITATION OF OLKARIA – Chumari A CASE STUDY PRESENTATION) (INTERNATIONAL 55 | GEOLOGY OF EXTENSIONAL-TYPE GEOTHERMAL SYSTEMS IN SYSTEMS GEOTHERMAL OF EXTENSIONAL-TYPE 55 | GEOLOGY – Rusoke UGANDA PRESENTATION) (INTERNATIONAL Session 8.2 Room 2 Treaty 107 | DISCRETE VS INTEGRATED PROJECT MANAGEMENT (IPM) AND PROJECT (IPM) MANAGEMENT VS INTEGRATED 107 | DISCRETE - DRILLING SERVICE FOR GEOTHER (IDS) CONTRACT INTEGRATED DRILLING IN INDONESIA – Agustino MAL PRESENTATION) (INTERNATIONAL 4 | FUTURE SUCCESS LOW TEMPERATURE MICRO GEOTHERMAL MICRO GEOTHERMAL TEMPERATURE LOW 4 | FUTURE SUCCESS – Knight POWER GENERATION PRESENTATION) (INTERNATIONAL 57 | COMPARISON OF WELLHEAD COMPLETION DESIGNS FOR WELLHEAD COMPLETION OF 57 | COMPARISON SPOOL AND IN INDONESIA. EXPANSION OPERATIONS GEOTHERMAL IN INDONESIA – Putri CASING HEAD COMPLETIONS PRESENTATION) (INTERNATIONAL 22 | CONCEPTUAL MODEL OF OUTFLOW ZONE IN MOUNT UNG - ZONE MODEL OF OUTFLOW 22 | CONCEPTUAL USING CENTRAL JAVA SEMARANG, SYSTEM, ARAN GEOTHERMAL ANALYSIS OF MANIFESTATION AND GEOCHEMISTRY GEOLOGY – Kencana PRESENTATION) (INTERNATIONAL

theelectricrevolution.co.nz HALLIBURTON | INDUSTRY UPDATE | INDUSTRY HALLIBURTON DEMETER | INDUSTRY UPDATE DEMETER | INDUSTRY UPFLOW | INDUSTRY UPDATE | INDUSTRY UPFLOW Lunch Industry Panel Session 8.1 Room 1 Treaty BASELOAD CAPITAL | INDUSTRY UPDATE | INDUSTRY CAPITAL BASELOAD MTL | INDUSTRY UPDATE | INDUSTRY MTL PUKEORA LAKEFRONT HOLDINGS | INDUSTRY UPDATE PUKEORA LAKEFRONT HOLDINGS | INDUSTRY Workshop close and awards Workshop Thursday 26 November (continued) 26 November Thursday 11.15 11.30 11.45 12.00 12.15 1.15- 2.15 2.15- 2.30 2.30 2.45 3.00 3.15

23-26 November 2020 | 21 Abstracts

3 | USING AIR-CAP TESTING TO MONITOR 4 | FUTURE SUCCESS LOW TEMPERATURE AND MEASURE GEOTHERMAL WELL CASING MICRO GENERATION INTEGRITY Robert Emrich Ralph Winmill 4080 Enterprise Way, Flowery Branch, , Wairakei , Georgia 30542 USA Te Aro Rd, Wairakei, New Zealand [email protected] [email protected] Keywords: Geothermal, Organic Rankine Cycle, Keywords: Well Integrity, Casing Integrity, Power Generation, Energy Efficiency Well Inspection, Well Control, Process Safety, Low temperature, micro geothermal Geothermal Well Casing generation offers significant renewable energy Monitoring and managing well casing integrity is opportunities worldwide. In the past low an important part of safely managing geothermal temperature geothermal and co-produced wells over their lifetime. A failure of casing fluids were considered a nuisance and integrity can lead to contamination of shallow uneconomical for power generation. Today aquifers and ultimately could even lead to an advances in technology are available to tap uncontrolled blowout. this prevalent resource to generate fuel-free, emission-free power, but unfortunately due to Historical methods for monitoring well casing a lack of knowledge on technologies available integrity involve go-devils, casing corrosion for sustainability, the industries opportunity caliper logging, camera surveys and pressure- to utilize low temperature resources is often temperature-spinner (PTS) surveys. Go-devils, overlooked. casing corrosion caliper logging and camera surveys can give indications of physical damage We are working diligently to overcome with no information on whether integrity is this knowledge gap, communicating with compromised, whilst pressure-temperature- the Industry that a solution exists for the spinner surveys can give results on well casing development of these resources and coupled leaking but only if the conditions are suitable to with the growth in electricity usage and indicate the loss of containment. environmental concerns of the use of fossil fuels for power generation, they should no longer be Session 5.1 overlooked.

Currently, the majority of geothermal power production that occurs is on the multi megawatt scale that require investment in resource development and infrastructure. There are however thousands of existing bore holes available from exploration for oil and gas, exhausted production wells, exploration for large geothermal resources and natural hot water springs that can be tapped for sub MW scale powerplants with minimal infrastructure and impact on local environments.

22 | 42nd New Zealand Geothermal Workshop This presentation will discuss the advances in It is not expected that new technology will technology enabling the economic use of low greatly reduce the cost of future geothermal temperature geothermal resources for power generation nor significantly extend the generation and application as bottoming plants geographical spread of its coverage to many to improve efficiency of existing geothermal lower-temperature resources. Thus, future large- infrastructure. It will cover the development scale development is likely to continue to be and application of Organic Rankine Cycle within the Taupō Volcanic Zone and at Ngāwhā technology incorporated in compact heat in Northland. to power generation equipment, the lessons Geothermal generation can run in a load- learnt, case studies of installed systems and following manner, but the most economic use of future developments including the optimization geothermal generation will remain as base load of equipment for use of low global warming because of the high fixed cost associated with potential refrigerants. the resource development. Previous studies in This presentation will also include incorporation New Zealand have over-stated the greenhouse of power generation as part of direct use gas (GHG) emissions of existing and future systems, containerized systems and potential geothermal plants. More specific figures are for efficiency gains in existing high capacity given based on actual recent data for developed geothermal plants. fields, as well as revised estimates for greenfields. The present MW-weighted average emissions Session 8.2 intensity for existing geothermal projects is 76 gCO2eq/kWh (2018), which has been steadily 5 | FUTURE GEOTHERMAL GENERATION declining (from 91g CO₂eq/kWh in 2015). STACK – FACTORS INFLUENCING NEW GEOTHERMAL PROJECTS IN NZ TO 2060 Greater future direct use of geothermal energy is generally expected to be complementary with Jim Lawless1, Bart van Campen2, Jim Randle3 rather than competitive to electricity generation 1 Lawless Geo-Consulting, New Zealand or to be based on lower-temperature resources. Scaling factors based on enthalpy and project 2 University of Auckland size have been applied to the power plant 3 GT Management, Jakarta portion of the project cost. On this basis capital costs range from 4,734 to 9,767 NZD/kW with a [email protected] weighted average of 5,782 NZD/kW. Keywords: Geothermal, generation, New Zealand, The total estimated available future geothermal 2060, GHG generation by 2060 is 1,035 MW. This total is This paper is based on a review that was slightly higher than previously presented (MBIE commissioned by the Ministry for Business, 2016), but it is likely that many projects will be Innovation and Employment (MBIE) in commissioned later than previously assumed. consultation with Transpower, with the objective Session 6.2 of estimating the possible timing and cost of future geothermal projects in New Zealand over a 40-year horizon.

Access to resources is likely to constrain the pace of development as well as project cost and electricity price. Regulatory and consenting difficulties may lead to delays for future projects.

23-26 November 2020 | 23 6 | AN UPDATED COMPUTER MODEL OF 8 | A PRACTICAL APPLICATION OF MONTSERRAT GEOTHERMAL FIELD CHLORIDE MASS BALANCE METHOD TO THE EVALUATION OF A GEOTHERMAL STEAM Marijn van den Heuvel1, Maella Bremaud2, GATHERING SYSTEM IN INDONESIA Mike O’Sullivan3, John O’Sullivan3, Joris Popineau3, Susana Guzman3, Zhilin James Dong and Richard J Adams Michael Gravatt3 and Graham A. Ryan4,5 MB Century, 166 Karetoto Road, Wairakei, 1 Department of Mechanical Engineering, New Zealand Eindhoven University of Technology, The [email protected] Netherlands Keywords: Geothermal, power station, tracer 2 Ecole nationale supérieure de géologie, testing, separator performance. Université de Lorraine, France A new geothermal power plant with an 85 MW 3 Department of Engineering Science, generation capacity was built last year in Muara University of Auckland, Auckland, New Zealand Laboh, West Sumatra, Indonesia. The double- 4 Montserrat Volcano Observatory, Flemmings, flash geothermal steam generation system Montserrat, W.I. consists of two high pressure separators and one low pressure separator. As the performance of 5 Seismic Research Center, University of the West the separators is critical to the safe and efficient Indies, St. Augustine, Trinidad and Tobago, operation of the turbines, a testing program West Indies. was developed and conducted to verify the [email protected] performance of the separators.

Keywords: Montserrat, geothermal model, A key indicator of separator performance is natural state, inverse modelling the steam dryness measured on the pipeline downstream of the separator. A natural tracer The model of the geothermal field on Montserrat mass balance method is used to measure Island, developed at the University of Auckland in the steam dryness, with chloride selected as 2018, has been updated in the following three ways. the natural tracer due to its abundance in First, the model grid was extended to the south-east geothermal fluids and being preferentially to include more of the area around the Soufrière dissolved in brine rather than in steam. Hills Volcano, and the grid was refined. Secondly, temperatures inferred from a seismic velocity Representative steam and brine samples anomaly model (Ryan & Shalev, 2014) were included were collected from steamline and brineline in the suite of data to be used for model calibration. test points downstream of the separators Thirdly, three software packages were used for and analysed for chloride and sodium in parameter estimation with the natural state model, the laboratory. These chloride and sodium namely: iTOUGH2, PEST and iWaiwera. iWaiwera concentrations are used to calculate the steam uses the adjoint method to evaluate derivatives dryness using a mass balance method. Special efficiently and therefore it was able to very quickly traversing isokinetic probes were developed and estimate a large number of model parameters. successfully used to collect representative steam samples in the tests. A good match to the downhole temperatures in wells Mon-1 and Mon-2 was obtained as well as a Session 6.3 good match to the inferred temperatures at three elevations.

Session 3.2

24 | 42nd New Zealand Geothermal Workshop 9 | THREE NEW HOT SPRING VENTS EXPOSED At Orakei Korako geothermal field, Taupo AT ORAKEI KORAKO GEOTHERMAL FIELD, Volcanic Zone, New Zealand, three new hot NEW ZEALAND spring vents appeared in 2019, underneath and adjacent to the boardwalk. These vents were Bridget Y. Lynne1,2 and Gary J. Smith2 buried and have now been reactivated following 1 University of Auckland, 70 Symonds St, a small hydrothermal eruption. Two of these Auckland, New Zealand vents currently have 98°C clear, blue water at their base while the third vent is steaming. Prior 2 Geothermal Scientific Investigations Ltd, to exposure of these three vents, this site had 11 Kyle Rd, Greenhithe, Auckland, New Zealand elevated near-surface temperatures for many [email protected] or years which we recorded at 100 °C at 0.5 m [email protected] depth during our repeated site visits. A survey undertaken in 2012 to assess heat migration Keywords: Reactivation of buried hot spring pathways at Orakei Korako documented vents, changes to surface activity, Orakei Korako, hydrothermal alteration in the shallow Ground Penetrating Radar. subsurface at the site where the three new vents are now visible.

Session 1.3

23-26 November 2020 | 25 10 | ON THE CHOICE OF PRIMARY VARIABLES 11 | DEVELOPMENT OF A TRANSIENT, MULTI- IN TRANSIENT GEOTHERMAL WELLBORE FEED GEOTHERMAL WELLBORE SIMULATOR MODELLING Ryan Tonkin, John O’Sullivan and Ryan Tonkin, John O’Sullivan and Michael O’Sullivan Michael O’Sullivan Department of Engineering Science, Department of Engineering Science, University of Auckland, Auckland, New Zealand University of Auckland, Auckland, New Zealand [email protected] [email protected] Keywords: wellbore, multi-feed, transient, Keywords: wellbore, multi-feed, transient, two-phase, simulation, validation two-phase, simulation, finite volume method, Simulation of the flow in a geothermal wellbore primary variables is an important reservoir engineering task, but Transient flow in a geothermal wellbore is most existing geothermal wellbore simulators modelled using equations for conservation can only deal with steady-state conditions. This of mass, momentum and energy. Additional paper discusses the theoretical background of constitutive equations that describe phase a transient geothermal wellbore model that is slip, heat transfer and frictional effects are currently under development. The simulator also required for model closure. The transient is capable of modelling transient single and wellbore simulator described in this paper solves two-phase flow in wells with multiple feed- discrete two-phase conservation equations zones. A geothermal wellbore simulator solves numerically using the Newton-Raphson the conservation of mass, momentum and procedure. Additionally, the constitutive energy equations governing the flow in a equation describing phase slip is included in geothermal wellbore. These, along with the the set of equations to be solved implicitly. additional equations required for model closure, This method requires four primary variables, are presented. These governing equations are however, the best choice of the primary variables discretised and solved numerically using the is not clear. This paper discusses the use of Newton-Raphson procedure. The simulator is different combinations of primary variables in tested using analytical solutions for simplified our transient geothermal wellbore simulator. single-phase flow situations. Steady-state The numerical performance of each model validation cases are presented for both single- is assessed using a set of problems that have feed and multi-feed wellbores and a simulation been developed to test the transient simulator. of the transient behaviour of a geothermal This suite of test problems covers a range of production well is presented as a test case. operating conditions and serves as a benchmark Finally, further applications of the simulator are for future simulator development. It was found discussed. that using pressure, temperature (swapped with Session 3.2 saturation for two-phase conditions), vapour velocity and liquid volume flux resulted in the best numerical performance for all cases tested.

Session 3.2

26 | 42nd New Zealand Geothermal Workshop 12 | AN UPDATED COMPUTER MODEL OF 13 | ACCURATE LOCATION OF FEED ZONES: THE ROTORUA GEOTHERMAL FIELD ASSESSING OBSCURATION BY THE LINER IN GEOTHERMAL WELLS Ken Dekkers2, Marcus van Vlijmen2, John O’Sullivan1, Michael Gravatt1, Ielish Goble and Katie McLean Joris Popineau1 and Michael O’Sullivan1 Contact Energy Ltd., , 1 Department of Engineering Science, Taupo New Zealand University of Auckland, 70 Symonds Street, [email protected] Grafton, Auckland 1010, New Zealand Keywords: Completion testing, stage testing, 2 Department of Mechanical Engineering, well testing, geothermal wells, cold water Eindhoven University of Technology, injection, perforated liner. 15 Groene Loper, 5600 MB Eindhoven, The Netherlands Feed zones in geothermal wells are typically identified primarily from pressure, temperature [email protected] and spinner (PTS) data captured with a downhole Keywords: Computer modelling, Rotorua tool during completion testing, when water is being injected into the well. Completion testing Two improvements have recently been made usually occurs after the slotted liner has been to the model of the Rotorua Geothermal Field, installed in the well, and it is frequently assumed developed at the University of Auckland. First, that feed zone locations are at least partially a finer, regular rectangular model grid is used. obscured by the presence of the liner. In some Secondly, a Leapfrog-based geological model wells there is also stage testing during drilling, to and an alteration model are used to better define aid the decision on whether to continue drilling the permeability structure of the computer or not. Critically, stage testing occurs prior to model. the installation of the liner, and also captures With a new regular rectangular grid, we can run PTS data. Some stage testing only captures data the model with AUTOUGH2 or Waiwera, and within the well casing down to the casing shoe. with the Waiwera version we are able to use However, there are a number of examples with iWaiwera for rapid parameter estimation (inverse sufficient PTS data captured in the open-hole modelling). section to allow comparison to the results from completion testing. These examples show that With this computer model, based on a better the location and nature of the feed zones can be geoscientific conceptual model, we have seen in much finer detail when the liner is not obtained a good match to the large suite of present. downhole temperatures and to the pressure histories measured in a small number of wells. The aim of this research is to quantify the degree to which the liner obscures the feed Session 1.2 zone locations by comparing temperature logs acquired during open-hole testing (stage testing) with those acquired after liner installation (completion testing). Several field examples are presented, from liquid-dominated wells in the Taupō Volcanic Zone.

Session 5.1

23-26 November 2020 | 27 14 | CAN THE REYKJAVÍK DISTRICT HEATING complex and costly, possibly making the system SYSTEM (DHS) BE USED AS A MODEL FOR A economically infeasible. Several other issues for ROTORUA DHS? A COMPARATIVE STUDY a Rotorua DHS were greatly simplified with the Reykjavík municipality offering the utility service. Mariana Zuquim1 and Penny Doorman2 The geothermal resource in Rotorua could 1 Faculty of Engineering, be more efficiently and equitably utilised for The University of Auckland, 70 Symonds Street, residential space heating. However it is expected Auckland, New Zealand that better results would be achieved by fine- tuning the Rotorua Geothermal Regional Plan 2 Regional Council, 5 Quay St. according to the local settings than replicating Whakatāne, New Zealand the Reykjavík DHS in Rotorua. [email protected] Session 4.2 Keywords: Rotorua, Reykjavík, geothermal, district heating system, DHS, surface features, 15 | PENTANT EVACUATION FOR BINARY reservoir, infrastructure, funding. PLANTS

The Rotorua geothermal field is managed by Leigh McLellan, Kiel Harpur and the Bay of Plenty Regional Council under the Viola Hoepfinger Resource Management Act and provisions of the Mercury, PO Box 245, Rotorua 3040, Bay of Plenty Regional Policy Statement and the New Zealand Rotorua Geothermal Regional Plan. The latter is currently being reviewed as is required every ten [email protected] years by the Resource Management Act 1991. Keywords: pentane, evacuation, binary plant, Feedback during initial community engagement Ngatamariki, geothermal power plant, vacuum stages of the review included questions around pump the potential for a district heating system (DHS) in Rotorua based on the experience of the Mercury owns and operates several Ormat Reykjavík DHS. This paper presents a high-level binary plants located in the North Island of desktop study comparing the Rotorua and New Zealand. For each site n-Pentane is the Reykjavík geothermal fields. Aspects such as motive fluid and its flammable nature presents historic background, current development model challenges with respect to maintenance activities for the fields, statistics of use, funding, costs, on pentane plants. Until recently Mercury has government input and administration of the field relied on specialized contractors or flooding are discussed. The Reykjavík DHS was a pioneer vessels with water to enable hot work such as engineering work which changed the way welding to take place on pentane equipment. Icelanders lived. It evolved over decades of trial With large binary units this approach is not and error and significant governmental support. always practical and for the past two years The Icelandic DHS suited perfectly a country Mercury have undertaken significant research with heat demand year-round and abundant and planning to enable the safe evacuation of geothermal resources, but a limited variety of pentane plant. other indigenous heating and energy options. A key focus for the project has been to assess Incommensurable differences between Reykjavík and reduce risks associated with the evacuation and Rotorua cities and access to the geothermal procedure. With guidance from Ormat and resource make the Icelandic DHS unsuitable for collaboration with other New Zealand pentane Rotorua. Some obstacles are technical, and while site operators Mercury have established a these could be overcome, solutions would be guideline for evacuation of pentane plants.

28 | 42nd New Zealand Geothermal Workshop Ngawha Expansion Project

The approach taken uses a combination of Keywords: Geoheat strategy, economic nitrogen purging and evacuation techniques development, New Zealand, Action Plan, to remove pentane from a unit. A key piece of strategy implementation, low carbon energy, equipment designed and fabricated by Mercury industrial symbiosis. is a portable pentane evacuation skid for use at The Geoheat Strategy for Aotearoa New Zealand any of their pentane sites. This paper discusses 2017-2030 is a cross sector initiative working to the effectiveness of the pentane evacuation, increase the direct use of geothermal energy. lessons learned along with Mercury’s plans to improve pentane safety in their plants. The Geoheat Strategy was formulated based on a consultative process undertaken in 2015 2017, Session 4.1 and the first Action Plan was delivered in 2018- 2019. This paper provides an update on strategy 16 | GEOHEAT STRATEGY FOR AOTEAROA implementation, and in particular, introduces the NEW ZEALAND – 2020 PROGRESS UPDATE second Action Plan, released in January 2020 for M Climo1, A Seward2, A Blair3, S. Bendall4 and the period 2020-2021. B Carey2 Discussed in this paper are: 1 Bridger Consulting, Christchurch, New Zealand • outcomes achieved through the 2018 and 2 GNS Science, 114 Karetoto Rd, SH1, Wairakei, 2019 period, Taupō, New Zealand • progress achieved overall towards the 2030 3 Upflow Ltd, PO Box 61, Taupō, Strategy objectives, New Zealand 3010 • mechanisms currently being used to deliver 4 Traverse Environmental, PO Box 245, the strategy outcomes, Taupo 3351 • review of Strategy direction, and [email protected] • insight into current and future activities.

Session 4.2

23-26 November 2020 | 29 17 | OPTIMAL SETTINGS FOR DIRECT numerical modelling to determine what rock GEOTHERMAL USE INVESTIGATED WITH properties and thermal characteristics result in NUMERICAL MODELLING usable low-temperature geothermal systems. We will distinguish key settings that are suitable Sophie Pearson-Grant1, Anya Seward2, for different direct use technologies such as Matthew Knowling3, Brian Carey2, and ground-source heat pumps, residential warm John Burnell1 water extraction or direct heating for small- 1 GNS Science, 1 Fairway Drive, Avalon 5010, scale commercial industry. We can then start Lower Hutt, New Zealand to build up a map of the most promising types of geothermal use for different regions in New 2 GNS Science. Wairakei Research Centre, Zealand. 114 Karetoto Road, RD4, Taupo 3384, New Zealand Session 4.2

3 School of Civil, Environmental and Mining 18 | NEW ZEALAND’S REGULATORY Engineering, The University of Adelaide, Adelaide, AND PLANNING FRAMEWORK FOR South Australia, 5005 Australia CONVENTIONAL GEOTHERMAL RESOURCE [email protected] USE

Keywords: Direct use, low-temperature D. Kissick1, S. Bendall1, M. Climo2 geothermal, numerical modelling, TOUGH2, 1Traverse Environmental, PO Box 245, Monte Carlo simulation Taupo 3351, New Zealand Geothermal energy has been used in the 2Bridger Consulting, PO Box 36-118, central part of the North Island of New Zealand Christchurch 8146, New Zealand since people first settled there. Traditionally it was used for bathing and cooking. During [email protected] the 20th century, uses expanded to include Keywords: regulatory framework, planning heating and cooling of buildings, green houses framework, review, permitting, consenting, and aquaculture farming. Direct geothermal resource consent, geothermal electricity, use tends to be located in areas where there governance, New Zealand, Geothermal: Next is a known heat source with easily accessible Generation (GNG), regional plan, statutory heated water; many of New Zealand’s direct framework, resource management. use applications are focussed within the , or in areas with hot springs In New Zealand, geothermal resources such as Hanmer Springs in the South Island. are treated as water resources, and their With the New Zealand government’s ambitious use is predominantly governed by broad targets to reduce fossil fuel dependencies, environmental resource management legislation. clean and efficient sources of energy will Geothermal use and development projects become increasingly important. Determining are authorised by resource consents under the the potential, and potential limitations, of Resource Management Act by regional and low-temperature geothermal energy will district councils. Projects of this nature must also be important to help in establishing the navigate a complex framework of interconnected contribution that it can make to the nation’s legislation with implications at national, regional energy ambitions. and district levels through policy documents and plans. This project aims to identify the ideal settings for low-temperature heat extraction. We will use

30 | 42nd New Zealand Geothermal Workshop This paper summarises the current regulatory Tapping into deeper supercritical resources to and planning frameworks that apply to access significant reserves of higher temperature the development and use of conventional (400˚C-600˚C), sustainable, renewable geothermal resources in New Zealand. This geothermal energy is not a new idea. Yet, present review was undertaken to inform studies on the levels of understanding are insufficient to offer suitability of the existing planning framework industry-ready solutions for New Zealand. for managing the potential future use of We are working to develop a New Zealand supercritical geothermal resources. supercritical heat strategy (2020-2050), looking to Poster accelerate from today’s understanding through to early deployment of applicable technologies 19 | NEW ZEALAND’S SUPERCRITICAL by 2040. Sector-wide roll-out aims to align with OPPORTUNITY: MOVING FROM POTENTIAL New Zealand’s aspirations to be “carbon zero” RESOURCE TO DEPLOYED TECHNOLOGY by 2050. The strategy will build on the scientific understanding of New Zealand’s supercritical M. Climo2, I. Chambefort1, B. Carey1, Simon resources, account for international experiences, Bendall3, A. Blair4 and propose work streams to address the 1 GNS Science, Private Bag 2000, Taupo 3352, technological, legal, regulatory, economic and New Zealand other challenges to utilisation of supercritical resources. 2 Bridger Consulting, PO Box 36-118, Christchurch 8146, New Zealand This paper presents the current state of knowledge on New Zealand’s supercritical 3 Traverse Environmental, PO Box 245, opportunity and outlines the intended strategic Taupo 3351, New Zealand review of barriers and opportunities, working 4 Upflow, PO Box 61, Taupo 3351, New Zealand with stakeholders across the New Zealand industry, researchers, business, Māori, and [email protected] Government. The critical challenge is to go Keywords: supercritical resources, strategy beyond conventional geothermal systems, in development, permitting frameworks, technology search of the scientific, technological, regulatory, deployment, de-risk investment, Geothermal: market and societal solutions that together, Next Generation, earth energy will de-risk and accelerate New Zealand’s supercritical exploration and development.

Session 5.3

23-26 November 2020 | 31 20 | GEOCHEMISTRY OF EXTENSIONAL-TYPE Soil-gas and gas-flux measurements along GEOTHERMAL SYSTEMS IN UGANDA Kibiro, Buranga, Panyimur, Katwe and Ihimbo hot springs revealed concealed deep penetrating Twesigye Benjamin structures which control geothermal activity. The Ministry of Energy and Mineral Development 3He/4He ratios of geothermal fluids from Kibiro P.O BOX 9, Entebbe, Uganda fault-bounded geothermal system suggest no deep mantle signature. Stable isotopic studies of [email protected] deuterium and oxygen-18 indicated high altitude Keywords: geochemistry, deep circulation, fluid sources. Normally geothermal fluids contain amagmatic, extensional <1ppm Mg content but most of Uganda’s hot spring waters contain 1-10ppm Mg suggesting The purpose of this paper is to explain mixing with surface cold waters. the geochemistry of Uganda’s amagmatic extensional-type geothermal systems, Poster particularly the origin of the chemical properties and corresponding reservoir properties. 21 | EXPERIMENTAL DETERMINATION OF This type of system is a fault bound deep RATE CONSTANTS FOR THE BREAKDOWN circulation system unlike magmatic systems OF THE ORGANIC TRACERS 2-NSA, 2,6-NDS, which rely on shallow magma chambers. 2,7-NDS, 1,5-NDS AND 1,6-NDS UNDER The fault zones are tectonically active which GEOTHERMAL CONDITIONS ensures deep circulation and high permeability. Lucjan Sajkowski1,2,, Bruce W. Mountain1 and Terry These amagmatic systems have low to M. Seward2 medium temperature sources with subsurface temperatures ranging between 100oC and 1 GNS Science, Department of Earth Resources 200oC. Deep circulation geothermal fluids are and Materials, Wairakei, New Zealand less chemically charged compared to those 2 School of Geography, Environment and Earth from magmatic systems due to low temperature Sciences, Victoria University of Wellington, sources. Geothermal fluids from most of New Zealand Uganda’s geothermal areas are of neutral to slightly basic pH (6.0-9.0) and can be classified [email protected] as fresh water to moderately saline based on Keywords: tracer studies, naphthalene disulfonic their recorded TDS and conductivity values. acid, naphthalene sulfonic acid, NDS, NSA, Their TDS varies depending on the surrounding experimental geochemistry. rocks through which the fluids flow from the reservoirs to the surface where they manifest as Naphthalene sulfonates are widely used in the hot springs. Fluids from South-Western Uganda geothermal industry as tracers. Experimental geothermal prospects have a relatively low Cl results show, however, that these compounds do concentration and are mainly classified as HCO3 have their temperature limits. Knowledge of the type or SO4 type. Fluids from Western Uganda rate of thermal breakdown is essential to ensure geothermal prospects have a relatively high Cl successful tracer tests. In addition, information concentration and are mainly classified as Cl- on the breakdown products could be useful HCO3 type or intermediate type with moderately in interpreting fluid temperature history. The high salinity in excess of 10,000 TDS. Possible main goal of this project is to broaden the subsurface temperatures for Uganda’s hot understanding of the processes taking place springs range between 100oC and 250oC based when these tracers are exposed to conditions on geothermometry and mixing models proving found in geothermal environments. they are low to medium temperature sources.

32 | 42nd New Zealand Geothermal Workshop The experiments were conducted to measure This research is conducted in the outflow zone of the rate of the thermal breakdown reactions. Mount Ungaran geothermal system, Semarang, Five polyaromatic (di)sulfonates: 1,5-naphthalene Central Java, Indonesia, i.e. Kendalisodo and disulfonate (1,5-NDS), 1,6-naphthalene surrounding which is located in the eastern disulfonate (1,6-NDS), 2,6-naphthalene and southeastern part of Mount Ungaran. The disulfonate (2,6-NDS), 2,7-naphthalene purpose of the study is to build the conceptual disulfonate (2,7-NDS) and 2-naphthalene model of the Kendalisodo geothermal system. sulfonate (2-NSA) were studied. Aqueous Methods used comprise of literature study, solutions containing NDS/NSA were sealed inside geological traverse mapping, water sampling, glass ampoules using an oxy-acetylene torch and geochemical study for anions, cations, and placed in cold-seal pressure vessels. These gas, and stable isotopes δ18O, δ2H, and δ13C were exposed to between 200°C and 330°C for analysis. Geothermal surface manifestation in the different times from 20 hours to 3 months. The study area includes Kendalisodo, Diwak, Derekan, experimental solution consisted 0.05M NaCl at and Kaliulo warm springs; with travertine and salt neutral pH. The various naphthalene sulfonates deposits in some areas. Fumarole and hot springs were analysed by high performance liquid appear in the upflow zone of Gedongsongo. chromatography (HPLC) using fluorescence In the study area, there are two geothermal detection. systems, i.e. Kendalisodo and Diwak system. These two systems are separated by the Old The rate constants were estimated by least Ungaran Caldera. Both systems are non-volcanic squares fitting of the results. These show and medium enthalpy systems. The Kendalisodo that NDS breakdown rates are temperature reservoir has a temperature of 170 ± 10˚C. The dependent. Stability increased as follow: hydrothermal fluid of the Kendalisodo system 1,5-NDS<1,6-NDS<2,6-NDS/2,7NDS <2-NSA. originates from meteoric water catchment on Additionally, 2-NSA and 1-NSA were detected the southeast slope of Mount Ungaran; the as breakdown products of naphthalene meteoric water is heated up by the remaining disulfonates. 2-NSA and 1-NSA were not stable heat of Mount Kendalisodo intrusion. The fluid at 300˚C. has experienced mixing with cold water before Session 6.3 discharge in the upflow zone at the Kendalisodo area. The Kendalisodo geothermal system, 22 | CONCEPTUAL MODEL OF OUTFLOW geologically and geochemically, is different from ZONE IN MOUNT UNGARAN GEOTHERMAL the main geothermal system of Mount Ungaran SYSTEM, SEMARANG, CENTRAL JAVA (Gedongsongo). The Diwak geothermal system USING GEOLOGY AND GEOCHEMISTRY OF has a reservoir with a temperature of 160 ± 10˚C. MANIFESTATION ANALYSIS The hydrothermal fluid of the Diwak system is also from meteoric water, which is heated up by Aditya Yuda Kencana and high heat-flow and/or overpressure system. The Niniek Rina Herdianita fluid then owsfl upward through the Derekan Geological Engineering Departement, Fault and discharges in the upflow zone as the Faculty of Earth Science and Technology, Diwak and Derekan warm springs. The fluid also Bandung Institute of Technology, Ganesha St, flows laterally through the Derekan Fault and Number 10, Bandung, Indonesia mixed with formation water to form Kaliulo warm spring in the outflow zone. [email protected] Session 8.2 Keywords: caldera, geochemistry, Kendalisodo, outflow, Ungaran.

23-26 November 2020 | 33 23 | A REVIEW OF SMALL-SCALE uses is greater. The author is very confident that GEOTHERMAL POWER PLANTS IN JAPAN Japan and New Zealand can fruitfully collaborate AND ITS OPPORTUNITIES FOR NEW in this area in terms of direct investment. Indeed, ZEALAND’S GEOTHERMAL BUSINESS The author is very positive for this and it is a chance for New Zealand business to expect Yoshifumi Imamura1, Isao Shiozaki2, some return and trade benefits. We can also sell Tadahiko Okumura2 our advanced New Zealand technologies and 1 New Zealand Trade & Enterprise, services in Japan such as subsurface analysis and c/o New Zealand Embassy, 20-40 Kamiyama-cho, any other hot-spring-related services. Shibuya-ku, Tokyo 150-0047, Japan In this paper, we want to share some hints for 2 Engineering Advancement Association of New Zealand businesses wishing to work in Japan, 3-18-19 Toranomon, Minato-ku, Japan and identify any possible opportunities for Tokyo 105-0001, Japan New Zealand businesses to work in Japan.

[email protected] Poster

Keywords: Japan, Onsen, small-scale 24 | GENDER MAINSTREAMING IN THE geothermal power plant, direct use DEVELOPMENT OF DIENG AND PATUHA The word ‘Onsen’ can be found in the oldest GEOTHERMAL FIELD, INDONESIA Japanese historical documents called ‘Kojiki’ Agdya Pratami Putri Yogandari, Aulijati written in the early 700s. As of the end of March Wachjudiningsih, and Supriadinata Marza 2019, there are 27,421 Onsen hot spring wells all over Japan. Historically, Japanese people have PT Geo Dipa Energi (Persero), Jakarta, Indonesia used these hot springs for bathing, and this is [email protected] associated with tourism and in many cases, they are used for medical purposes. These historical Keywords: Gender, Gender Mainstreaming, Onsen are specifically defined by Japanese Social, Geothermal Development law in the Hot Spring Act 1948 and these hot Indonesia ranks 116th out of 189 countries on springs are subject to protection. Today, 87% of the 2018 Gender Development Index (GDI). direct use cases of geothermal energy are for Nationally, female development still lags behind those Onsen while its use has also diversified compared to men. From 2010, the development to a variety of purposes such as greenhouses of men has a “high” status with a Human for horticulture, aquaculture to grow not only Development Index (HDI) above 70 while the prawns but also eels, tilapia, softshell turtles, tiger development of women is still in the range of puffer and sturgeon at different locations. In the 60s and has a “moderate” status. This is what recent years, hot spring water has also been used causes Indonesia’s GDI to still be below 100 over to generate electricity and there are 60 such the period 2010-2017. power plants in Japan. All of them are less than 2 MW installed capacity and most of them were In Indonesia, the female position in many built after 2011 when the Japanese government categories (representation, employment, introduced the Feed-In Tariff system. etc.) is lower compared to that of men. The development of a geothermal project provides What does this mean for New Zealand’s hope and opportunity for the communities geothermal businesses? There may be hints for in the project area, including female groups/ the direct use of geothermal energy in New villagers. In developing geothermal projects in Zealand since in the Japanese case use is unique, Patuha (West Java) and Dieng (Central Java), very diversified and the number of those direct

34 | 42nd New Zealand Geothermal Workshop Indonesia, PT Geo Dipa Energi conducted a 4 Mercury, 283 Vaughan Road, Rotorua, gender assessment. Low participation of women New Zealand in public consultations was found, as well as 5 Contact Energy, Ltd, Private Bag 2001, poor access to various job opportunities in Taupo 3352, New Zealand geothermal projects. [email protected] In addition, based on available data, there are still gaps in employment opportunities between Keywords: Rantau Dedap, Muara Laboh, men and women in geothermal projects in Ngatamariki, Wairakei, borehole image log, both regions. One of the main causes is the fracture, geomechanics local norms that lead women to carry multiple There is a fast-growing inventory of studies on responsibilities in domestic and public spheres, borehole image logs acquired in geothermal thereby reducing the capacity of women to reservoirs as more operators elect to deploy this access various opportunities from the project. technology. Our contribution to this inventory is This paper presents challenges and opportunities to illustrate how judicious use of these data may in mainstreaming gender at a geothermal project reveal the geologic controls on permeability. in Indonesia, in particular during the preparation We also provide an open source Python library period in which the gender assessment that enables others to replicate the methods was being conducted. The series of public described herein. Our study includes a discussion consultations and women’s group discussions of geometric sample bias, as well as those data indicated that geothermal project development integrity and geological factors that influence should consider the impact on women and fracture frequency. We also demonstrate other vulnerable groups. The project developer slip tendency modelling as an approach to should clearly state the opportunities for female identifying fractures that may be relevant beyond participation in project implementation, as the borehole wall, which is key for geothermal part of the company’s commitment towards wells where thermal stresses have enhanced improving the local socioeconomic standards. both the number and apparent aperture of fractures at the borehole wall. We illustrate Session 4.2 these methods using seven well case studies from a wide range of lithologies, four reservoirs, 25 | APPROACHES TO IMAGING FEEDZONE and two tectonic settings—one dominated by DIVERSITY WITH CASE STUDIES FROM a volcano-tectonic rift and the other a mega- SUMATRA, INDONESIA AND THE TAUPŌ shear zone. The reservoirs are Muara Laboh and VOLCANIC ZONE, NEW ZEALAND Rantau Dedap in Indonesia and Ngatamariki and Irene Wallis1, Julie Rowland1, David Dempsey2, Wairakei in New Zealand. George Allan4, Ridwan Sidik3, Rudy Martikno3, Session 1.3 Katie McLean5, Mauliate Sihotang3, Herwin Azis3, Marino Baroek3

1 School of Environment, University of Auckland, 23 Symonds Street, Auckland, New Zealand

2 Engineering Science, University of Auckland, 70 Symonds Street, Auckland, New Zealand

3 PT Supreme Energy, Menara Sentraya, 23rd Floor. Jl. Iskandarsyah Raya No 1A, Jakarta 12160, Indonesia

23-26 November 2020 | 35 26 | NGATI TUWHARETOA GEOTHERMAL 27 | GEOTHERMAL STEAM TURBINE ASSETS LTD REBOILER PLANT WATER/ DEPOSITION FUNDAMENTALS AND STEAM CHEMISTRY IMPROVEMENTS TO PROPOSED IAPWS GEOTHERMAL STEAM RESOLVE ONGOING CORROSION ISSUES PURITY LIMITS AND PREVENT FUTURE TUBE FAILURES David Addison1 and Ian Richardson2 David Addison1, Nik Vandervegte2 and 1 Thermal Chemistry Limited, New Zealand Nellie Olsen1 2 Contact Energy, New Zealand 1 Thermal Chemistry Limited, New Zealand [email protected] 2 Ngati Tuwharetoa Geothermal Assets Ltd, New Zealand [email protected]

[email protected] Keywords: steam turbine, steam purity, deposition, scaling, corrosion. Keywords: Corrosion, reboiler. Hydrogen sulfide, sodium hydroxide, film forming substances Geothermal steam turbines are prone to forming significant turbine mineral deposits under The Ngati Tuwharetoa Geothermal Assets Ltd suboptimal steam purity and quality conditions. (NTGA) Kawerau reboiler plant has suffered These deposits can then lead to operational from major corrosion and plant failure issues and maintenance issues that are detrimental to since commissioning, including the premature turbine performance, reliability and availability complete replacement of the tube bundles. These corrosion related failures have occurred The mechanisms related to how deposits form due to water/steam chemistry issues and within geothermal steam turbines are discussed interactions with plant materials not being in relation to both vaporous and mechanical fully considered and understood in the design transport of impurities in steam. Saturated and process of the plant. Superheated steam conditions and their impact on deposition within a geothermal turbine are In 2018 a major root cause analysis was reviewed. The formation and behavior of the undertaken into the failures that included liquid films that form within geothermal steam a detailed chemical and metallurgical turbines are outlined and the impact on these investigation and successfully identified the liquid films by reheating due to heat transfer failure mechanisms. A number of simple across a turbine disk or shaft is discussed. chemical treatment changes, including hydrogen sulfide neutralization, pH correction and the Session 3.1 application of corrosion inhibiting film forming substances (FFS), were carried out to successfully 28 | SWANHILD: NUMERICAL PRESSURE mitigate ongoing corrosion of the plant and to TRANSIENT ANALYSIS USING THE VOLSUNG significantly extend asset life. GEOTHERMAL RESERVOIR SIMULATION PACKAGE Session 3.1 Katie McLean1, Peter Franz2 and Jonathon Clearwater2

1 Contact Energy Ltd, Private Bag 2001, Taupo 3352, New Zealand

2 Flow State Solutions Ltd, 67 Hamon Place, Rotorua 3015, New Zealand

36 | 42nd New Zealand Geothermal Workshop [email protected] 29 | HYDROGEOCHEMICAL CHARACTERISTICS OF GEOTHERMAL WATER Keywords: Swanhild, Volsung, well testing, IN MOUNT LAWU, INDONESIA pressure transient analysis, numerical D.N. Sahdarani1, M.A. Ponka1, D.A. Yoga1, The need for numerical models for geothermal D.T. Kurniadi1 and Supriyanto1,2 pressure transient analysis (PTA) has been long recognised. Until recently the only tools/software 1 Geological Science, Faculty of Mathematics available for PTA in the geothermal industry have and Natural Sciences, Universitas Indonesia been based on analytical models, which are too 2 Geophysics, Faculty of Mathematics and simplistic to represent geothermal wells. The Natural Sciences, Universitas Indonesia lack of numerical tools for PTA led to the creation of the numerical PTA framework (McLean and Kampus UI Depok, Depok 16424, Indonesia Zarrouk, 2017), which is a set of guidelines on [email protected] how to set up and run numerical PTA models using TOUGH2 and Python. Analysis of the model Keywords: Mount Lawu, Indonesia, results and comparison to field data required hydrogeochemical. skills in writing auxiliary computer scripts by the Mount Lawu is a stratovolcano located in individual reservoir engineer. Despite assistance the border of Central and East Java province, from the many functions built into Python, Indonesia. Mount Lawu holds a vast potential numerical PTA was still relatively time-consuming of geothermal energy indicated by widely and cumbersome to perform. Specialized distributed thermal manifestations. This study software was necessary to bridge this gap, and aims to evaluate the hydrogeochemical hence Swanhild was developed, based on the characteristics on the western side of Mount numerical PTA framework guidelines. Lawu and also to create a simple preliminary This study presents testing of the new Swanhild hydrogeochemical model based on geological software application. Swanhild forms part of and geochemical data. Surface manifestations the Volsung geothermal reservoir simulation showed all types of chloride, sulphate and package and is specifically designed to carbonate water are present among both hot run numerical PTA simulations using the and cold fluid chemistry with pH ranging from standardised approach as specified by the 1-2 and 6-7 on the central and proximal facies numerical PTA framework. The application of Mount Lawu respectively. Isotopic analysis makes numerical PTA straightforward, including of thermal water indicates both magmatic model setup and inversion with field data. The water and meteoric water that circulates within model matching can be performed manually Mount Lawu geothermal system. Fe and As or automated using non-linear regression. concentrations appear to be higher in some A comparison between Swanhild and the manifestations indicating intense rock-fluid TOUGH2/Python implementation of the interaction from the reservoir to the surface. numerical PTA framework across a range of Moreover, Na/K geothermometer indicates an model parameters reveals no practical difference intermediate-high enthalpy system. Based on in the model results, thus validating Swanhild these findings, a hydrogeochemical model was for use in numerical PTA. Software licenses for synthesized and also proved that Mount Lawu is Swanhild are available for free as part of an a volcanic geothermal system with intermediate- ongoing effort to enable and promote quality high enthalpy energy. PTA in geothermal wells. Session 7.3 Session 1.2

23-26 November 2020 | 37 30 | SIGNIFICANCE OF PRESSURE LET DOWN 31 | A NEW NUMERICAL MODEL OF STATION IN MITIGATING EFFECTS OF SILICA AMATITLAN GEOTHERMAL SYSTEM, PRECIPITATION IN STEAM PIPELINES: A CASE GUATEMALA STUDY OF OLKARIA 280MW PROJECT Enrique A. Porras and Julian Xicara Joseph Chumari1 and Daniel Odongo2 Ormat Technologies, inc. 6140 Plumas street, 1 Kenya Electricity Generating Company PLC, Reno, NV 89519-6075, USA. Kenya [email protected], [email protected] 2Kenya Electricity Generating Company PLC, Kenya Keywords: Reservoir modeling, Dual-porosity, [email protected] New generator type DELT, AUTOUGH2, TIM, Py-TOUGH, Calcite scale. Keywords: PLDS, De-superheating, Silica The Amatitlán geothermal field has a high- In 2012, KenGen began construction of two temperature reservoir with feed zone geothermal power plants: 140MWe Olkaria IV temperatures and pressures in most of the and 2 additional units, units 4 & 5 (Olkaria IAU) production wells reflecting boiling conditions. adding140MWe to Olkaria I and thereby increasing The existence of a shallow vapor-mobile two- power generation in Kenya by 280MWe. The two phase region (i.e., a “steam cap”) and a deeper power plants have turbine inlet pressures of 6.0 extensive two-phase reservoir were confirmed by bara and 5.0 bara for Olkaria IV and Olkaria IAU two wells (AMF7 and AMF8). Gas concentrations respectively. This meant the steam gathering are variable but modest calcite scaling exists in systems would also operate at that pressure. AMF1RD. Temperature distribution suggests that While the project was in progress, a new the upflow of the Amatitlán geothermal system optimization study reported that the deeper takes place beneath a significant area of the wells in Domes, East and North East fields which active Pacaya volcano. The revised conceptual serve the power plants with steam tap fluids model suggests that the outflow of the system from reservoirs that are rich in silica. The issue flows laterally toward Lake Amatitlán. was compounded by high enthalpies of the A three-dimensional numerical model wells averaging 1790kj/kg to 2300kj/kg thereby consisting of 11,240 grid blocks was developed increasing silica solubility and chances of for reservoir simulations. Natural-state and precipitation in steam pipelines. production/injection simulations for near 12 The concern raised resulted in KenGen years of exploitation were conducted using this incorporating Pressure Let down Stations (PLDS) model and AUTOUGH2 simulator, TIM pre-and in the two power plants that would maintain the post-processor and Py-TOUGH scripts. TIM steamfield pressure at the maximum but within and Py-TOUGH were essential for optimizing the constraints of the already selected equipment, the model block structure, adding meteoric and then expand the steam adiabatically to drop recharge and background heat into the model, its pressure to required values. assigning the topography to the top surface of the model and to represent Lake Amatitlán, all This paper will use the case study of these power required for dealing with the complexity of the plants to highlight the significance of the Pressure real geothermal system. Simulated temperatures Let down Stations in controlling the effects of and pressures distribution in natural state match silica deposition in steam gathering systems. field data measured prior exploitation. For Session 7.2 production history matching a dual porosity model was developed and it reproduces current

38 | 42nd New Zealand Geothermal Workshop flow rates and enthalpy of produced fluid by the of the world has been met with a number production wells. The model also reproduces of non-technical barriers which when not pressure transient data of one monitoring properly handled can have devastating effects well (AMF7). The effects of calcite scaling on on projects. These non-technical barriers production parameters of well AMF1RD is include lack of awareness and information by addressed in the model mainly by using the new stakeholders on the concept of geothermal generator type DELT, Yeh, A., et. al (2012). energy, very high economic expectations and various environmental misconceptions about The model is capable now for predictions. such developments. The Kibiro Geothermal As an example, a base case scenario was run; prospect has hot springs that have been held this base case scenario was divided into two in high regard culturally by the Bunyoro Kitara different cases: Scenario one considers continue Kingdom and its subjects for centuries. Therefore, production as it is now for the next fifteen years the proponent has to convince the Kingdom without taking into account scale in the best and its subjects that these developments will production well AMF1RD. The second scenario have no effect on their cultural sites. However, is the same case as scenario one but it takes these barriers can easily be mitigated by carrying into account scale in well bore and formation out continuous and extensive geothermal of AMF1RD. Results of simulated prediction sensitization, workshops targeting the relevant scenarios are that by considering the scale issue stakeholders. The Government of Uganda during the simulation study, the simulated MW applied a number of strategies that include tours thermal are more realistic that the case that to Olkaria Geothermal project in Kenya, site doesn’t consider scale. The difference in terms of meetings, social media outreach and information MW thermal for both scenarios is about 2% lower sharing, one on one interaction with opinion for the most realistic case. Simulations also show leaders, workshops with the cultural leaders a decline on MW thermal for both cases of about of Bunyoro Kitara Kingdom. These strategies 0.90 MW thermal per year. whose aim is to obtain a social license, gain Poster trust and approval for the project have yielded good results. This notwithstanding, there are a 32 | COMMUNITY ENGAGEMENT IN number of barriers that are encountered by the GEOTHERMAL DEVELOPMENT IN UGANDA. project proponents which include mobilization CASE STUDY OF KIBIRO GEOTHERMAL of funds to implement the different engagement PROSPECT strategies.

Brian Aijuka1,2 Session 4.2

1 Ministry of Energy and Mineral Development, Plot 29/33-Kampala Uganda

2 Directorate of Geological Survey and Mines, Plot 21-29, Johnston Road P.O.BOX 9, Entebbe [email protected]

Keywords: Community engagement, barriers, awareness, culture

Geothermal development in Uganda like any other development projects in other parts

23-26 November 2020 | 39 34 | COMMON PRACTICE OF FORMATION formation during drilling operation, completed EVALUATION PROGRAM IN GEOTHERMAL by the pros and cons. Those techniques DRILLING including drill cutting examination and analysis, drilling data interpretation, rock coring analysis, Vicky R. Chandra1, Ribka F. Asokawaty2, both conventional and sidewall coring, and Dorman P. Purba2 well-logging, including PTS logging, acoustic 1 PT Geo Dipa Energi, Jl. Warung Buncit Raya and electric borehole imaging, and also other No.75, Jakarta, Indonesia logging activity. All those techniques expected to enhance the better understanding of subsurface 2 PT Rigsis Energi Indonesia, Equity Tower, 49th geology and improve the drilling operation. Floor, Jl. Jend. Sudirman, Jakarta, Indonesia Session 7.3 [email protected]; vickyraychandra@gmail. com [email protected] dorman. 35 | CUSTOM PDC BITS SIGNIFICANTLY [email protected] INCREASE DRILLING PERFORMANCE IN Keywords: formation evaluation, cutting, coring, TAUHARA GEOTHERMAL DRILLING PROJECT borehole image, drilling, geothermal Ellie Lock1, Rob Tipples2, Basil Ching2 and Formation evaluation program in drilling Pawl Victor2 operation, particularly geothermal drilling, is very 1 Contact Energy, Wairakei Power Station, much determined by the purpose and objective Te Aro Road, Taupō, New Zealand of drilling itself. During early exploration phase, the formation evaluation program is carried out 2 National Oilwell Varco, Inc. (NOV), 7909 by collecting as much subsurface information as Parkwood Circle Drive, Houston, TX 77036, possible. This was applied because of available United States subsurface data to support the development [email protected] geothermal project are very limited. On the other hand, the program is very influenced and directly Keywords: PDC technology, drill bits, drilling involve to the drilling operation that might risks performance, fixed cutter bits the drilling operation, in term of well stability The use of polycrystalline diamond compact and well cost perspective. Thus, the effective and (PDC) bits in geothermal applications has always efficient techniques are highly required in the presented challenges in terms of bit durability, making of proper formation evaluation program. directional response, and economic viability of The main purpose of formation evaluation is such bits in these applications. to get a better understanding of subsurface This paper focuses on two sets of challenges geology and developed geothermal system so associated with designing PDC bits in 20¾ in. the best future strategy of field development and 12¼ in. sizes to drill through hard volcanic can be determined. By doing this evaluation and sedimentary formations in the Tauhara while drilling, it will give an advantage to the geothermal field of New Zealand. drilling operation itself. Knowledge of the real- time drilled formation, in term of its behaviour, This paper discusses PDC drill bit design, characteristic, and composition, will help the cutter selection, root cause analysis of drilling improvement of drilling performance and dysfunctions, and other limitations affecting increase the well success ratio. overall drilling efficiency. It will also demonstrate drilling parameter sensitivity analysis, drilling This paper will present the available technical practices used to reduce bit damage while guidelines that can be applied to evaluate the

40 | 42nd New Zealand Geothermal Workshop improving overall drilling performance, and the Access to water, as managed under the Resource economics for both sections. Management Act 1991 (RMA) is becoming increasingly constrained in New Zealand. For the above project, two bespoke bits were Geothermal drilling operations require relatively designed, built, and tested. This paper presents large amounts of surface water albeit on a the results of these bit runs, the learnings made, variable and infrequent basis to provide for and future iterations. It will show that the tailored drilling mud and circulation fluids. As fluids are bits outperformed all previous bit runs in the “lost” during drilling to the deep underground Tauhara field and saved the Operator significant formations, more fluids and water are required drilling time. to provide for safe and successful drilling Session 5.1 operations. This paper identifies key policy issues involved with surface water allocation 37 | CHANGING RESOURCE MANAGEMENT and use, through the lens of geothermal drilling OF SURFACE WATER ALLOCATION TO MEET and identifying several methods to effectively DRILLING RIG DEMANDS manage the resource during a well programme. Investigations into current water provision within Mitch Collins two Council regions are discussed, as well as Mercury NZ observations of how water is to be managed in New Zealand. [email protected] Session 1.1 Keywords: Resource Management Act 1991 (RMA), Water Supply, Surface Water, Drilling, Loss Control, River, Allocation.

Eastland Generation is part of Gisborne-based infrastructure company Eastland Group. Our operations include hydro generation near Wairoa and two geothermal power plants in Kawerau. As local leaders in energy, we’re proud to be a sponsor of the 42nd Geothermal Workshop. eastland.nz

23-26 November 2020 | 41 40 | A COMPARATIVE WATER GEOCHEMISTRY show definite trend similarities, especially for STUDY OF FIVE GEOTHERMAL FIELDS IN THE sodium concentrations between 1978 – 1984. TAUPO VOLCANIC ZONE: ATIAMURI, MOKAI, Specific reasons or events causing similarities to NGATAMARIKI, WAIKITE, AND WAIOTAPU occur between Ngatamariki and Waiotapu are not known. It has long been unclear if Waikite Jesse L. Lebe1, Bridget Y. Lynne2,1 and Waiotapu are hydrologically connected. 1 University of Auckland, Geochemistry trends identified in our study for Department of Engineering Science, these two systems suggest they have dissimilar 70 Symonds St, Auckland 1142, New Zealand water chemistry, which may indicate separate geochemical controls. Caldera boundaries and 2 Geothermal Scientific Investigations Ltd, lithological conditions surrounding the caldera- 11 Kyle Rd, Greenhithe 0632, Auckland, bounded Mokai and Atiamuri systems are New Zealand identified as important factors for isolating fluids [email protected]; [email protected] from these systems and minimising external influences on observed geochemical parameters. Keywords: Water chemistry, chloride, silica, Our water chemistry study offers insights into sodium, potassium, magnesium, boron comparing geochemistry trend changes at a Our study involved a comparison of hot spring regional scale by observing different geothermal geochemistry data collected between 1905 and systems with distinctive conditions. 2009 from five geothermal fields in the Taupo Poster Volcanic Zone (TVZ), New Zealand. Atiamuri, Mokai, Ngatamariki, Waikite, and Waiotapu were 42 | A REVIEW OF THE HYDROGEOLOGY OF chosen as the geothermal systems for this study THE TAUHARA DOMESTIC BORES, TAUPŌ, for their east-west and north-south coverage NEW ZEALAND. of the central TVZ, their comparative data availability, and for representing development Jesse L. Lebe and protected systems. One neutral-chloride hot Waikato Regional Council, Private Bag 3038, spring that best represented the deep reservoir Waikato Mail Centre, Hamilton 3240 fluid was chosen for each geothermal system. Water-type and geoindicator ternary diagrams [email protected] were utilised for observing changes in each Keywords: Domestic bore, direct use, Taupo, hot spring overtime. Chloride (Cl-), silica (SiO2), Tauhara, hydrogeology, aquifer sodium (Na), potassium (K), magnesium (Mg), and boron (B) were the main parameters used for Five hundred and twenty-four domestic bores interpreting reservoir conditions and associated have been installed for water and space heating near-surface influences. Semi-qualitative in Taupō township, mainly within the resistivity concentration trend maps were constructed for boundary of the Tauhara geothermal field. comparing geochemistry trends between the Geochemistry data indicate that the dominant five fields. The geothermal systems of Mokai water type extracted from the allocated aquifer and Ngatamariki as well as Atiamuri and Waikite is steam-heated waters. Due to minimal data which represented our East-West distribution existing on the lithological conditions of the of systems showed minimal similarities in bores, lithostratigraphic data from well THM-18 is geochemistry trends. Ngatamariki and Waiotapu used for interpreting the subsurface stratigraphy were compared as the spatial relationship of the allocated aquifer area. No significant between these two fields is consistent with variations in temperature-elevation relationship the major structural trend of central TVZ. They are observed at different geographical areas

42 | 42nd New Zealand Geothermal Workshop 43 | PATCHING HELE-SHAW CELLS TO SIMULATE SILICA SCALE DEPOSITION IN DISCRETE FRACTURE NETWORKS

Pouria Aghajannezhad and Mathieu Sellier

Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand

Keywords: Silica Deposition, Computational Fluid Dynamics, Hele-Shaw Cell, Discrete Fracture Network

Due to mineral deposition in geothermal reservoirs, the electrical production of geothermal power plants decreases over time. Specifically, silica can form extremely hard and dense scales not only in power-plant equipment and pipelines but also within and around wells, restricting flow and reducing power-plant efficiency. Understanding the effect of silica scaling on flow rates can inform the required maintenance during different stages of the across Taupō township. Elevation and bore geothermal plant lifetime. Accordingly, a detailed depth measurements suggest that the Oruanui analysis of silica scale growth offers powerful Formation is the most common lithological unit insight to predict the productive lifetime of from which hot fluids are extracted. The Upper the reservoir and mechanical infrastructures. Huka Falls Formation is intersected by fewer Fluid within many geothermal reservoirs is bores and records lower temperatures than the largely transported along a network of fractures. overlying Oruanui Formation. Fluids exceeding However, available simulation methods to study 160 °C were encountered in the Middle Huka mineral deposition within large-scale fracture Falls Formation, however the formation is a networks are computationally expensive. We less practical drilling target than the Oruanui have developed a new modeling framework Formation aquifer for future domestic bore based on representing individual fractures using drilling due to its situation at significantly the Hele-Shaw cell analogy and simulating greater depths. The Oruanui Formation is the fracture networks by connecting these Hele- most productive and most ideal target zone for Shaw cells together using pressure constraints at future fluid extractions due having a reliable intersecting nodes of the computational mesh. high temperature resource at a relatively shallow This methodology allows the rapid computation depth. Future monitoring of the bores could of flows in realistically large fracture networks. create a better understanding of the relationship This paper will discuss how this modeling between the domestic bores and surface framework can be used to study the transport of geothermal features and streams, which have diluted specious in rock fractures, which provides seen a general decline in discharge in recent a backbone for the simulation of silica scale years. deposition in a discrete fracture network.

Session 1.3 Session 1.2

23-26 November 2020 | 43 44 | GREENHOUSE GAS EMISSIONS FROM which are reinjected back into the reservoir. NEW ZEALAND GEOTHERMAL: POWER Accounting for the gases in the condensates GENERATION AND INDUSTRIAL DIRECT USE results in a more accurate calculation of the actual emissions intensity. Another nuance of Katie McLean1,2, Ian Richardson1,2, the emissions intensity for geothermal is that Jaime Quinao1,3, Tom Clark4, Lara Owens4 the numbers do not account for the benefits 1 New Zealand Geothermal Association of geothermal fluids for direct use applications such as industrial process heat. Direct use 2 Contact Energy Ltd, Private Bag 2001, projects utilise energy directly, as thermal energy, Taupo 3352, New Zealand which is not accounted for in the emissions 3 Ngati Tuwharetoa Geothermal Assets, intensity data which only deals with electrical Rotorua NZ energy. Nevertheless the benefits of geothermal direct use are a very real, if invisible, part of 4 Mercury Ltd, 283 Vaughn Road, Rotorua NZ the geothermal emissions intensity story, and [email protected] examples are given.

Keywords: Carbon dioxide, methane, Session 1.1 greenhouse gas, geothermal, emissions, direct use. 47 | SINTER-FORMING SPRINGS OF THE WAIKATO REGION, NZ Greenhouse gas emissions for geothermal power stations in New Zealand are reported annually Katherine M Luketina1, Jesse Lebe1, under current regulations. The CO2 and CH4 Ashley D Cody2 and Bridget Lynne3 emissions data are combined and reported as 1 Waikato Regional Council, 418 Grey St, one CO2-equivalent (CO2e) emissions factor. In Hamilton, New Zealand combination with the amount of steam used each year, and the MWh (net) of electricity 2 [email protected] generated that year, the overall geothermal 3 Bridget Lynne, Geothermal Scientific emissions intensity for each power station can Investigations Ltd, [email protected] be calculated as gCO2e/kWh(net). A recent study presented the emissions intensity for the [email protected] 12 major geothermal power stations in New Keywords: Waikato region, sinter, hot springs, Zealand focusing on the calendar year 2018, geysers. with data back to 2010 for some stations. In this paper the emissions intensity is presented Sinter-forming springs and geysers are among for the calendar year 2019, and compared with the rarest, the most vulnerable, the most trends from previous years. In New Zealand spectacular and the most prized among the the emissions intensity for geothermal power Waikato Region’s geothermal surface features. generation is on average an order of magnitude This paper summarises a Waikato Regional lower than for fossil fuels. Council (WRC) Technical Report titled Sinter- forming Springs and Geysers of the Waikato In most cases the geothermal emissions intensity Region (Cody et al, 2020, in prep) herein after numbers are calculated assuming that all of the referred to as “Sinter Springs”, that provides an CO2 and CH4 present in the steam entering the inventory of sinter-forming springs and geysers power station are released to the atmosphere in the Waikato Region (the Region), notes on during the power generation process. However their location, activity, characteristics, and any in some geothermal plant designs a fraction threats that they face. It is hoped that this report of the gases are retained in the condensates,

44 | 42nd New Zealand Geothermal Workshop will assist in the preservation of these features by Therefore, WRC undertakes geophysical, providing a guide to assist further monitoring. geochemical, and ecological monitoring of the region’s geothermal environment, stores the data There are 169 sinter-forming springs in the in a variety of databases depending on the data Waikato Region, down from 668, and 51 geysers, type, interprets the data and publishes reports in down from 161, in the 1950s. The greatest loss of several media for different audiences. The WRC features was caused by the inundation of many website provides environmental articles for a features at Orakei Korako when the Ohakuri Dam lay audience, Technical Reports, environmental was constructed for hydroelectric electricity indicators, and downloadable data. Papers are generation, and by the extinction of features on publicly available through the International the Wairakei-Tauhara Geothermal System due to Geothermal Association (IGA) papers database the large-scale extraction of deep geothermal and through other open-access journals. fluid for the Wairakei Power Station. Monitoring is undertaken to determine the Ohaaki, Mangakino, Atiamuri, Ngatamariki, Mokai, natural state of the regional geothermal and Rotokawa have also lost sinter-forming resource, its variability, any trends and to identify springs due to inundation of springs when any anthropogenic changes. This informs the hydro-electric lakes were created. Tokaanu- policy development, resource allocation and Waihi and Rotokawa have non-sinter-forming organisation decision making processes to springs that are affected by lake and river level ensure that the resource is managed sustainably. management. Monitoring is funded through resource consent WRC’s policy framework under the Resource holder annual charges and the general rate Management Act 1991 (RMA) protects these levied on regional landowners. This small income features. Consequently, there has been little stream is augmented by collaboration with and change in numbers since the 1990s when the support of other research bodies such as Crown policy was formed. Research Institutes (CRIs) and universities who Session 1.1 have central government research grants.

WRC researchers have had significant success in 48 | TWENTY-FIVE YEARS OF GEOTHERMAL developing or supporting the development of MONITORING BY WAIKATO REGIONAL new monitoring techniques including remote COUNCIL: EMBRACING CHANGE, sensing technology to provide system-wide and COLLABORATION, AND INNOVATION multi-system monitoring as well as interaction Katherine Luketina and Jim McLeod with groundwater and surface water, geothermal ecologies and the gradation from geothermal to Waikato Regional Council, 401 Grey St, non-geothermal environment. Hamilton, New Zealand Change is constant in our monitoring [email protected] programmes as we embrace new information- Keywords: geothermal, monitoring, RMA, gathering technologies, data collection, storage, PSInSar retrieval, analysis and interpretation applications, and communication media. Collaboration with Waikato Regional Council (WRC) has a statutory tangata whenua on Matauranga Maori physical obligation under the Resource Management and meta-physical monitoring is becoming more Act 1991 to monitor the state of the regional and more a part of what we do. geothermal environment, keep records, and make those records available to the public. Session 2.2

23-26 November 2020 | 45 50 | BLACK TERRACE, ROTOMAHANA There are indications from LIDAR of a partially preserved crater rim deposit around the inferred Phil White1, Andrew Lorrey2, J-M Woolley2, southern edge of the crater. Paul Vidanovich3 and Tom Dronfield4 Ground Penetrating Radar (GPR) revealed 1 Panda Geoscience Limited, Taupo, NZ possible normal fault features close to where 2 NIWA, Auckland, NZ the western crater rim was inferred to lie, and features that might represent a buried, partial 2 Paul Vidanovich Consulting Limited, Auckland, ejecta apron to the west of the buried crater rim. NZ Passive seismic tomography data revealed a 4 Resource Potentials, Perth, Australia lateral east-west change, with hard reflectors [email protected] located 35-50m below the ground surface within the bounds of where the crater floor is inferred Keywords: Black Terrace, Rotomahana, sinter, to lie. GPR, passive seismic tomography. Session 1.3 Prior to 1886 there was widespread thermal activity around Lake Rotomahana. In addition to 51 | ENVIRONMENTAL BASELINE SURVEY the Pink and White terraces, there were smaller FOR GEOTHERMAL DEVELOPMENT: CASE sinter terraces, including one known as Black STUDY KIBIRO GEOTHERMAL PROSPECT, Terrace, or Te Ngawha a Te Tuhi. All of those UGANDA features were either ruined or buried during the 1886 Tarawera eruption. The former locations of Oris Ouma the Pink and White terraces are now beneath the Ministry of Energy and Mineral Development enlarged Lake Rotomahana, but the Black Terrace P.O.Box 9, Entebbe, Uganda site to the northwest is outside the former and current lake. [email protected] , [email protected] About two months after the Tarawera eruption, a hydrothermal eruption at the location of Black Keywords: Geothermal, environment conditions, Terrace threw out rocks and mud, and the crater baseline data, mitigation measures. grew to ~180 m in diameter over two days The shift to environmentally friendly energy before activity gradually waned over the next sources is one of the main items on the agenda few weeks. Being surrounded by hills covered in of global environmental debates. Geothermal unconsolidated eruption debris, this crater was energy is one of the resources that often are rapidly infilled over subsequent years. It is no located in remote, forested and wildlife areas, longer obvious on maps, aerial photos, or in the whose environment is a source of social and field. economic necessities for Ugandans. Therefore, Through a combination of geological and in order for government and stakeholders geophysical techniques, we believe that we to assess the impact of geothermal projects have relocated the buried Black Terrace Crater, on the environment, the developer must although it remains to be seen whether any sinter prepare a detailed Environmental and Social is preserved at depth. Impact Assessment (ESIA) for the project. The current state of physical, social and economic Proximity to the crater is indicated by boulders (up environments is defined in baseline surveys to 1.5m diameter) that overlie Rotomahana Mud before a project begins and are necessary for near the site. Those boulders are mostly rhyolite, the design and assessment of any project. but include several fragments of silica sinter.

46 | 42nd New Zealand Geothermal Workshop The potential impacts of a project cannot be 52 | CO2 DISCHARGE FROM LAKE ROTOITI, determined without knowing the existing state NEW ZEALAND of the environment. Baseline surveys will also be Tsung-Han Jimmy Yang1,2, Isabelle Chambefort1, used to monitor the effects of projects during Agnes Mazot1, Michael Rowe2, Brad Scott1, operation, such as physical, biological and Nick MacDonald1, Cynthia Werner3, socioeconomics aspects. The baseline data is Cornel de Ronde5, Tobias Fischer4. built through collection and analysis of existing data, community consultation programs and 1 GNS Science, Wairakei research Centre, specific field surveys. An Environmental and New Zealand Social Impact Assessment (ESIA) is then carried 2 School of Environment, University of Auckland, out to discover early enough, if there would be New Zealand any adverse effects on the environment and local ecosystems. An ESIA would ensure that any 3 U.S. Geological Survey, David A Johnston developments undertaken are environmentally Cascades Volcano Observatory, Vancouver, U.S.A. benign and socially acceptable to stakeholders 4 Department of Earth and Planetary Sciences, including geothermal energy development University of New Mexico, Albuquerque, U.S.A. partners. In this article the Kibiro geothermal project serves as example. This project is [email protected] anticipated to have both positive and negative Keywords: Lake Rotoiti; CO2 flux; dissolved gases. environmental impacts based on baseline studies. However, the negative impacts can be Twenty percent of the surface area of Okataina contained through recommended mitigation Caldera is covered with lakes. Lake Rotoiti located measures. at the northwest edge of Okataina Caldera, hosts numerous underwater hydrothermal vents. Session 1.1 Western Lake Rotoiti has relatively shallow waters (10-40m) and is closely associated with Tikitere and Taheke geothermal fields. Plumes of gas and bubbling warm water can be observed in the lake resulting in a 10-20 MW geothermal heat flux of Central Basin located at the centre part of Lake Rotoiti. In this study, we present the results of a lake survey that focuses on surface CO2 emission using the floating accumulation chamber method and sequential Gaussian simulation for processing the data. In addition, dissolved gas composition and surface CO2 flux measurement give us a better understanding of the degassing pathways and mechanism of the geothermal fluids in Lake Rotoiti. The result of this lake survey benefits from the comparison of natural greenhouse gas output of Rotoiti to other volcanic lakes in Okataina Caldera and in New Zealand.

Session 6.3

23-26 November 2020 | 47 55 | GEOLOGY OF EXTENSIONAL –TYPE a value of 0.2 RA was obtained (Kato ,2018) GEOTHERMAL SYSTEMS IN UGANDA therefore no signature was indicated. The fact that the Kibiro prospect area is not proximal to Angel Rusoke young volcanic/magmatic rocks and the absence Ministry of Energy and Mineral Development, of the mantle signature, supports the presence Uganda. of extensional-type system. Soil gas and gas flux measurements have indicated high permeability Directorate of Geological Survey and Mines, concealed fault-bounded geothermal systems Uganda. at Kibiro, Buranga and Panyimur areas. During [email protected] exploration studies in Uganda, the exploration targets are at the points where the escarpment Keywords: deep circulation, magmatic, and the basin intersect, this is believed to be the amagmatic, extension-type geothermal systems location of the rift bounding faults controlling Geothermal systems in East Africa are either the up flow of geothermal fluids. magmatic or amagmatic/extensional-type Session 7.2 systems. Magmatic driven systems rely on shallow magma chambers as their heat source 56 | GENERATOR EXCITATION SYSTEM for example in Ethiopia and Kenya while the REPLACEMENT IN GEOTHERMAL POWER extensional-type systems are associated with STATIONS – MERITS AND PITFALLS deep seated magma chambers. This clear distinction is highlighted in the subsurface Generoso Paloso Jr.and Dennis Preston temperature differences seen in the western and Aecom NZ Ltd, 8 Mahuhu Cr, Auckland, eastern branches of the East African Rift System. New Zealand Most of Uganda’s geothermal systems are non- magmatic deep-circulation/extensional-type [email protected], dennis.preston@ systems similar to the Great Basin in the USA and aecom.com Western Turkey. In many respects, they typify Keywords: Excitation, generator control, system other fault-controlled geothermal systems that upgrade are driven by deep circulation of ground waters. At these rift fault-bounded geothermal systems, Some geothermal power stations exceed their fluid movement is controlled by the permeable projected operating life by adopting life- rift fault zone that bounds the rift valley. During extension techniques. While some mechanical the rift formation in Uganda; there was extension, equipment in power station can readily exceed fracturing and thinning of the crust causing the their design life, most of the control equipment mantle to become elevated which results in need replacement due to obsolescence and areas of elevated heat fluxes that are exploration difficulty getting technical support. targets for geothermal resources. This paper presents the options available for The heat that drives these amagmatic systems the replacement of ageing excitation system, is believed to result from active/extensional which is one of the major components that tectonics that permit the deep circulation of control the operation of turbine-generators. meteoric fluids through high angle faults and The performance requirements, functions and elevated heat flow that raises the temperature elements of modern excitation systems are of fluids to 150˚C and above. The 3He/4He discussed as an overview. The main drivers ratios of geothermal fluids from fault-bounded to proceed with replacement projects are Kibiro Geothermal systems were measured to elaborated with consideration of transmission determine if a mantle signature was present, system requirements, as well as long-term plans

48 | 42nd New Zealand Geothermal Workshop and objectives from generation companies. 57 | COMPARISON OF WELLHEAD Technical issues and pitfalls in the retrofit design COMPLETION DESIGNS FOR GEOTHERMAL process need to be considered to avoid delays OPERATIONS IN INDONESIA: EXPANSION during installation work. The timeframe to SPOOL AND CASING HEAD COMPLETIONS complete the installation and wiring works is Frilla Ranti Putri1, Dicky Alamsyah1, Daniel limited as these are done during scheduled plant Adityatama1, Rany Putri1, Sahat Nainggolan2, outages. Issues that are specific to geothermal Andri Burnama3 and Adi Krishamidan4 plant applications are deliberated with consideration of technologies currently available 1 PT. Rigsis Energi Indonesia, Equity Tower 49th in the market. The upgrade work has to consider Floor, SCBD, Jakarta 12520, Indonesia the interfaces between the excitation system and 2 Professional Drilling Consultant, other equipment, such as control system DCS, Bintaro, Banten, Indonesia electrical protection relays, dependable power supplies, measuring devices, and generator. 3 DSV Consultant, Balikpapan, Indonesia Experiences on excitation replacements projects 4 Professional Drilling Consultant, Bintaro, in geothermal power plants are shared to Banten, Indonesia provide generation companies some guidance in doing similar retrofit projects. [email protected]

Session 3.1 Keywords: Geothermal Wellhead, Wellhead Completions, Casing Head Flange, Expansion Spool, Geothermal, Drilling, Indonesia

Geothermal wellheads shall be designed to operate during the life of the well. In a hot, acidic, and corrosive geothermal operating conditions, the selection of wellhead completion is critical. The purpose of this study is to compare the conformity of two wellhead completion designs for application in Indonesia: expansion spool completion and casing head completion. Using cross-sectional analysis, this study assessed wellhead designs currently available in the market and comparing the results against technical judgements. This study also discusses the advantages and disadvantages of both designs, and the rationale behind the current design preferences in the geothermal industry in Indonesia.

Session 8.2

23-26 November 2020 | 49 59 | PRE-INDEPENDENCE AFRICA: A LOST country governments. The stand out is Kenya OPPORTUNITY FOR GEOTHERMSAL with a ranking of 9th rank among geothermal RESOURCE DEVELOPMENT top ten countries in the World. Djibouti’s current geothermal development status is attributed to Ralph K.B Nyakabwa-Atwoki the above ingredients in addition to the creation Sustenersol Uganda Limited of geothermal corporate bodies, namely: The Geothermal Development Company Ltd (GDC) [email protected] and Djibouti Office for Geothermal Energy Keywords: Africa, colonialization, diet, European, Development (ODDEG), respectively. geothermal, hominin fire use; human evolution, Conversely, the AGRCs who are currently independence, manifestations, lagging in the development of their geothermal Paleo-Indians, settlers. resource the slow progress is related end to Paleo-Indians, settlers living around hot springs the absence of some of the above ingredients were the first to explore and utilize geothermal thus necessitating their governments and resources in North America over 10,000 years policymakers to create or enhance their policy ago. European settlers moving westward framework to ensure the rapid development of probably encountered hot springs in Yellowstone geothermal energy in Africa. area and large scale use of hot springs energy in Session 7.3 la Grande, Oregon was recorded in 1862. Only 16 years later in 1878, explorer Stanley reported 62 | DIGITAL TWINS FOR THE GEOTHERMAL on the geothermal manifestations in pre- INDUSTRY: THEORY AND PRACTICE independence Africa in Burundi. Wei Yu1, Mohammad Dabbour1, Geothermal based electric power generation was Matthew Proctor1, David I. Wilson2, invented in Italy in 1904 and a feasibility study Isuru Udugama3, Rosalind Archer1 and Brent was carried out in 1911 in the now Democratic Young1 Republic of Congo (DRC) but the first use of geothermal energy for power production did 1 The University of Auckland, New Zealand not occur in Africa until 1952, when a plant 2 Auckland University of Technology, producing 550.000-kWh of electricity per year, New Zealand was constructed at Manono Province (DRC) in the now Democratic Republic of Congo 3 Technical University of Denmark, Denmark (DRC). So why have not more African countries [email protected] developed their geothermal power resources to date? The only exception being Kenya generate Keywords: Digital twin, geothermal industry, 667 MW of geothermal electricity. dynamic geothermal plant modelling, decoupling model Geothermal resources remained undeveloped until the African Geothermal Resource countries The term ‘digitalisation’, currently popular in (AGRC) attained independence. Some countries many industrial sectors, refers to the construction have developed strategic geothermal energy of computer models intended to improve policy, institutional, and regulatory frameworks production and efficiency. The ‘digital twin’ can for de-risking geothermal projects and also have be considered as one of the core concepts of the considered the development of requisite human digitalisation, and while still at the conceptual resources. the continent’s Geothermal projects stage for many manufacturing operations, there in the 21 AGRC are largely financed by regional are examples from the power industry - such programmes, international agencies and the as the Digital Wind Farm from GE Renewable

50 | 42nd New Zealand Geothermal Workshop Energy used to optimise turbine operations, Māori. The OVC is also a nested caldera complex, and improved maintenance planning of the one of two giant active calderas of the Taupō EDP (Energias De Portugal) Alqueva II hydro Volcanic Zone (TVZ), ranked as New Zealand’s power plant using a Digital Hydro Plant. In this highest threat volcano. In-situ, sub-surface paper, we will present results from our recent observations required to better understand two projects on the concept of linking digital interactions between volcanism, rifting, fluid twins within the NZ geothermal industry. The circulation and the deep biosphere are sparse. first is dynamic modelling of a geothermal We propose the INTERACTION (Interactions power plant, and the second is an exploration between life, rifting and caldera tectonics in of the economic optimisation when coupling Okataina) scientific drilling programme to both process and reservoir simulators to provide provide rock and fluid samples, downhole accurate prediction of both reservoir and plant measurements and a base for a long-term behaviours over the life time of the plant. observatory. Downhole samples and data, and The gaps between theory and practice are new high-resolution ground-based surveys summarised and the anticipated future trends in near the borehole will refine and fill gaps in digital twins for the benefit of the NZ geothermal the extensive geophysical, geological and industry are also highlighted. geochemical datasets collected across the OVC and wider TVZ region since the 1950s, Session 4.1 and advance fundamental concepts of caldera systems globally. 63 | RATIONALE FOR THE SCIENTIFIC DRILLING PROJECT “INTERACTION”: Scientific drilling at the OVC, coupled with INTERACTIONS BETWEEN LIFE, RIFTING extensive stakeholder engagement will lead AND CALDERA TECTONICS IN OKATAINA to improved resilience to natural hazards and sustainable management of groundwater and Cécile Massiot1, Tiipene Marr, Ludmila geothermal resources. Close collaboration with Adam2, Shane Cronin2, Edward Bertrand1, Māori will achieve both scientific and cultural Fabio Caratori Tontini1, Geoff Kilgour4, Sarah D. outcomes. New geothermal concepts (heat Milicich1, Craig Miller4, Alex Nichols4, Matthew source, permeability and recharge), geophysical Stott3, Guido Ventura5, Pilar Villamor1 and Paul data acquisition and new technology White4 deployment, will help future geothermal 1 GNS Science, Lower Hutt, New Zealand development in the central TVZ and elsewhere. Altogether, scientific drilling at the OVC will 2 University of Auckland, Auckland, New Zealand advance our understanding of: (1) drivers to 3 University of Canterbury, Christchurch, volcanic eruptions, feedbacks between volcanic New Zealand and seismic events, caldera evolution; (2) large- scale hydrology and magmatic systems; and (3) 4 GNS Science, Wairakei, New Zealand diversity, function, and geological processes that 5 INGV, Roma, Italy support deep subsurface microbial activity and response to a highly active geosphere. At these [email protected] early stages of planning, we invite contributions Keywords: scientific drilling, mātauranga Māori, to the concept of this project in the exceptional interactions, caldera, rift, biosphere, hydrology, OVC settings and strengthen linkages with Okataina Volcanic Centre other ongoing research and geothermal drilling programmes. The Okataina Volcanic Centre (OVC) in Aotearoa, New Zealand is of high cultural significance to Session 2.3

23-26 November 2020 | 51 64 | EFFECTIVE TURBINE PLANT OUTAGE 7. Technical communication and decision mak- EXECUTION ing during the outage

Pieter Krige1 and Andrew Nish2 8. Reporting on the completed outage

1 ProGen Principal Engineer, 18/21 Railside Place, 9. Post outage actions and planning for future Dinsdale, Hamilton, New Zealand outages

[email protected] Session 4.1

2 Mercury Turbine Specialist, 283 Vaughan Road, 66 | CULTURAL VIEWS, PERSPECTIVES Rotorua, New Zealand AND OBSERVATIONS OF THE HEALTH [email protected] AND WELLBEING OF THE ROTORUA GEOTHERMAL SYSTEM Keywords: Turbine, outage, maintenance Sharon Porter1, Roku Mihinui1, Lorraine Hall2, The results of a systematic approach to several Reg Naera3, Fred Clubb3, Lani Kereopa3, extraordinary turbine maintenance outages that Kataraina George4 and Elva Conroy5 were executed over one year by ProGen as the service provider will be discussed. All of these 1 Tuhourangi Ngāti Wahiao, Rotorua, outages were conducted successfully within New Zealand the time and budget parameters set. There 2 Ngāti Hurunga Te Rangi, Rotorua, New Zealand were no commissioning or operational issues encountered upon return to service. All of the 3 Ngāti Whakaue, Rotorua, New Zealand outages were planned to a tight schedule based 4 Ngāti Kea Ngāti Tuarā, Rotorua, New Zealand on optimizing historical performances. Although emergent work was discovered during most of 5 Conroy and Donald Consultants Ltd, Pāpāmoa, the projects, the work was able to be managed New Zealand within the allowed time frame and within the [email protected] planned budget. Keywords: Rotorua, Māori, mātauranga, mauri, The paper will discuss the challenges faced and cultural. successes achieved with the execution of these outages. It will focus on the principles followed Te Ahi Kaa Roa are a collective of representatives to ensure the outcomes achieved. from the hapū and iwi who have maintained continuous occupation of Ōhinemutu, The principles discussed will be: Whakarewarewa and Ngapuna villages in 1. Partnership relationship between the supplier Rotorua since pre-European times. and the owner/operator Ahi Kaa refers to the ‘burning fires of occupation’, 2. Planning for the outage using historic and and the whānau who reside in these villages forecasted findings have a long and unique relationship with the geothermal resources, features and activity 3. Plant life cycle managing and forecast around them. Each geothermal tāonga or 4. Preparation for execution done to the correct feature is named and ‘known’, in terms of their level characteristics, behaviours and perceived personalities. Their mātauranga, which includes 5. Decision making during the complete process intergenerational knowledge, is built upon leading up to the outage sensory-based tohu or indicators. 6. Execution of the outage

52 | 42nd New Zealand Geothermal Workshop Council has legal requirements and obligations While there are similarities in what is measured in to Māori under the Treaty of Waitangi, Resource cultural and contemporary terms (e.g. behaviour Management Act 1991 and Local Government of geothermal features), the Māori worldview Act 2002. Because of their intergenerational highlights that the environment and all it knowledge and experience, Bay of Plenty sustains (including people) is interconnected and Regional Council (Council) initiated the cannot be looked at in isolation. establishment of the group as one way to enable There has been a significant change in and ensure a tangata whenua lens or perspective geothermal use and management over time by regarding the management of the Rotorua tangata whenua due to the intergenerational Geothermal System and that mana whenua impacts of colonisation and resultant loss of are afforded a clear voice in the review of the control over their natural resources. Subsequent Rotorua Geothermal Regional Plan (Doorman, land use and development within the city, and Bhana & Camburn, 2020). the bore closure programme in the 1980s have While not the sole focus of the group, a occurred without iwi consent or input. key output of this relationship has been Te Ahi Kaa Roa hope the knowledge and the collation of cultural views, perspectives mātauranga shared as part of the current and observations of the current health and work with Council will help to inform future wellbeing of the Rotorua Geothermal System. management and monitoring of the system. This paper focusses on this aspect of the groups work acknowledging that their involvement 1 taonga are prized and protected as sacred in Council’s process and aspirations for the possessions of the tribe. The term carries a deep management of the Rotorua Geothermal system spiritual meaning and taonga may be things that are broader. cannot be seen or touched.

Session 2.2

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23-26 November 2020 | 53 67 | POIHIPI GEOTHERMAL POWER PLANT 70 | INVESTIGATION AND APPLICATION OF WATER COOLING SYSTEM – TAKING A FLASHING FLOW NOZZLES TO MITIGATE HOLISTIC APPROACH TO INVESTIGATING GEOTHERMAL TURBINE LIFE REDUCTION AT PROBLEMS AND IMPLEMENTING SOLUTIONS T. Misa, K. Harwood and C. Morris Morris Young1, 2 and Sadiq J. Zarrouk2 Contact Energy, Wairakei Power Station, 1 Contact Energy Ltd., Wairakei Power Station, New Zealand Taupo, New Zealand [email protected] 2 Department of Engineering Science, Keywords: steam impurities, turbine, flashing University of Auckland, Private Bag 90210, nozzle, steam separation, steam scrubbing. Auckland, New Zealand Because flash steam is not completely dry [email protected] after processing in the separation equipment, Keywords: Cooling water, microbiological pipelines and demisters are used to remove the control, algae, biocides, Sulphur Oxidising remaining moisture together with condensation Bacteria, geothermal, Wairakei, Poihipi. formed during transmission. If they are not fully effective, the result is scaling of turbine The type of equipment comprising a geothermal inlet nozzles, erosive wear of turbine internals, power station main cooling water system can corrosion of alloy blade paths and rotor forgings. have a significant influence on the cooling water This significantly reduces the economic life of chemistry, sulphur deposition and micro- and steam turbines. This issue of poor steam quality macro-biological control in addition to the and purity is common to many geothermal reservoir steam chemistry. A holistic approach plants worldwide, and prevalent in stations with is best when investigating problems to better separators nearby. understand the system and how best to implement solutions. Poihipi Road Power Station Investigation determined that significant is the only geothermal steam turbine power moisture travels downstream of the separators station in New Zealand to have a shell-and-tube as droplets less than 10 micrometers in size. (surface) condenser, which has a significant Preventing the formation of these small sized influence on the cooling water chemistry droplets results in a significant reduction of compared to a direct-contact condenser. Prolific mist borne-impurities that are resistant to algae growth on the also resulted conventional methods of gravity, centrifugal or in fouling throughout the cooling system and impingement separation. required frequent mechanical removal which Using the TRIZ (Theory of Inventive Problem increased the risk of dispersing into the air any Solving) methodology, a systematic review of Legionella bacteria that may have been present 34 engineering options to improve the steam with the algae. purity at Te Mihi Power Station was conducted. This paper provides an overview of the Importantly, this drew on knowledge from investigation approach performed to better outside the geothermal industry. The main understand the issues with the cooling water solution selected was the application of flashing system and how best to address them. flow nozzles instead of orifice plates, or control valves, to minimise the creation of droplets < 10 Session 4.1 micrometers in diameter when producing flash steam. Plant tests following installation measured a significant reduction in the total mass of

54 | 42nd New Zealand Geothermal Workshop mineral impurities flowing through the Te Mihi Keywords: Strainers, filtering, debris, scale, solid Power Station low pressure steam system. removal, solid waste management, cleaning, maintenance, separators. This was a low cost but effective improvement, avoiding invasive modifications to the steam Geothermal debris from flowing geothermal system. Minimising the creation of droplets wells is a common occurrence in geothermal smaller than 10 micrometers is an important plants and needs to be managed to avoid design consideration for future steam field damaging critical equipment such as heat and station developments around the world. exchangers, turbines, pumps, or reinjection Furthermore, the internal design of cyclone systems. Slotted well liners, strainers and liquid/ separators and transmission systems should solid separators are examples of equipment used avoid sharp edge flow shedding which can for this purpose. This paper reviews equipment increase creation and entrainment of small designs developed in New Zealand to manage droplets. debris around steam fields between 1988 and 2020. Sources, types of debris and its impact Session 5.2 on plant operations and maintenance are also described. A discussion around learnings based 71 | MANAGING DEBRIS IN GEOTHERMAL on field operations is presented, as well as PRODUCTION FLUID suggestions for debris management equipment Alexandre Rivera Diaz, Julie Chiquet and Kevin improvements. Koorey Session 4.1 MB Century, 166 Karetoto Rd. Wairakei, Taupo, New Zealand

[email protected]

23-26 November 2020 | 55 75 | USE OF ICE PLUGS IN GEOTHERMAL process industries in a variety of applications, but ANTI-SCALANT TUBING SYSTEMS there currently exists no documented evidence of their use in geothermal anti-scalant tubing William Duran1, Ben Drew , Gary Earl1 and Nelson maintenance. Cumare2 This paper discusses the use of ice plugs in 1 Western Energy Services, 132 Rakaunui Road, geothermal anti-scalant tubing operations, and Taupō, New Zealand how they have provided a simple and inexpensive 2 Mercury NZ Limited, 33 Broadway, Auckland, solution in contrast to a full tubing retrieval while New Zealand still addressing the well control risk of the cut and re-join method. [email protected] Poster Keywords: anti-scalant tubing, geothermal, chemical injection, scale formation, ice plugs 76 | INTEGRATION OF THE CALCIUM SILICATE Anti-scalant tubing is commonly used in (CASIL) TECHNOLOGY INTO GEOTHERMAL geothermal wells to allow chemical injection POWER GENERATION TO PREVENT SILICA of anti-scalant fluids from the surface, delaying DEPOSITION scale formation downhole. This tubing is James H. Johnston, Thomas Borrmann, Michael intended to be continuously exposed to severe Schweig, Mathew J. Cairns, H. Putri Fraser and well conditions creating a need for monitoring Sami Aljohani and inspecting the injection string periodically. One of the methods used to inspect the tubing School of Chemical and Physical Sciences, Victoria is called tubing lift. This consists of retrieving part University of Wellington, PO Box 600, Wellington of the anti-scalant tubing string from the well. 6140, New Zealand 2 This procedure moves the localised stress point [email protected] on the tubing string and also allows inspection of part of the anti-scalant tubing at the surface. Keywords: Silica scale prevention, calcium silicate technology, geothermal energy, enhanced Over time, this excess tubing collected at the electricity generation, reduced maintenance, surface becomes problematic, taking up space direct use, mineral extraction, paper, building, at the wellhead, and needs to be removed. environmentally beneficial applications. A common solution to this problem is to cut and re-join the tubing with the slack removed. Silica supersaturation in geothermal brine results Unfortunately, this process has the inherent risk in the formation of intractable silica scale deposits that when the tubing is cut, for a short period, in pipes, heat exchangers and reinjection wells. the well remains open to the atmosphere. To This scale prevents the full effective utilisation of avoid this exposure, the alternative is to retrieve geothermal resources for electricity generation the entire tubing string followed by unspooling and heat recovery applications. It is a major & spooling, cutting and re-running the string problem worldwide. Also, process equipment in the well. However, this is a timely and costly and reinjection wells can be blocked, which endeavour for such a small change in the anti- necessitate costly maintenance and plant scalant tubing string. downtime. Current approaches attempt to address the problem by using higher steam/ To improve the cut and re-join process, the idea water separation temperatures to reduce silica of a temporary well barrier was explored, and saturation, acid dosing or additives to retard silica ice plugs were found to be a suitable solution to polymerisation. However, the use of these is not well containment. Ice plugs have been used in wholly satisfactory; silica still precipitates and

56 | 42nd New Zealand Geothermal Workshop electricity generation and heat recovery remain 80 | ECOLOGICAL INFORMATION FOR compromised. GEOTHERMAL SITES IN WAIKATO REGION

We have developed our proprietary new Sarah M. Beadel, Chris M. Bycroft, Kelvin M. Lloyd, nanostructured calcium silicate, CaSil, technology and William B. Shaw to address the problem and are demonstrating Wildland Consultants Ltd, 99 Sala St, Rotorua, it in an automated pilot scale operation at New Zealand. Wairakei. We remove the problematic dissolved silica as a novel CaSil material. This lowers [email protected] the silica saturation index (SSI) substantially Keywords: Indicators, geothermal vegetation, below 1. The technology is applicable to a rare species, monitoring, pest animals, pest range of brine compositions, temperature and plants. pressure conditions. The technology opens up opportunities for further mineral extraction (e.g. Geothermal ecosystems are some of the most lithium, base metals). Additionally, more heat threatened ecosystems in the Waikato Region, energy can be safely extracted from the brine having undergone significant reductions without causing silica scaling during electricity in extent and condition. Five geothermal generation or industrial direct use applications. ecosystem types have been recognised in New Because of its unique surface chemistry the Zealand. These are all considered to have been CaSil material does not stick to metal pipes, naturally rare prior to human colonisation of New significantly reducing maintenance costs for Zealand (Williams et al. 2007) and have all been process equipment and reinjection wells, and identified as Critically Endangered (Holdaway plant downtime. et al. 2012). Waikato Regional Council (WRC) has an inventory of geothermal sites in the Waikato The CaSil material is a useful product that Region, which contains a summary of ecological has a range of industrial and environmental information prepared by Wildland Consultants remediation applications. These applications (2014). utilise the unique 3D framework structure of CaSil, which provide it with high liquid absorbent A framework of ecological indicators assessing and surface area properties. By careful control geothermal extent, condition, and protection of the calcium silicate chemistry and some status was developed recently (Wildland post-separation treatment, new CaSil materials Consultants 2015), but information gaps meant are generated with properties suitable for high that this framework could not be applied across volume applications in the building, paper, all Waikato geothermal sites. Key gaps identified paint, absorbent, mining and environmental were lack of information on non-vascular plant remediation industries. species, herpetofauna, fish, invertebrates, and fungi. In addition, relatively few sites Session 5.2 had any quantitative monitoring or detailed ecological restoration plans. A framework was therefore developed to prioritise the filling of these information gaps by surveying priority geothermal sites.

Session 1.1

23-26 November 2020 | 57 81 | WELL PERFORMANCE DIAGNOSTICS 83 | B-VALUE MAPPING FOR VOLCANIC- AND FORECASTING USING THE GUDRUN RELATED GEOTHERMAL SYSTEM: A CASE WELLBORE SIMULATOR - CASE STUDIES STUDY OF NEVADO DEL RUIZ VOLCANO, FROM KAWERAU, NEW ZEALAND COLOMBIA

Jaime J. Quinao1, Peter Franz2, and Pablo Aguilera1,3, Ludmila Adam1 and Jonathon Clearwater2 Geremew Lamessa2

1 Ngati Tuwharetoa Geothermal Assets Ltd. 1 School of Environment, University of Auckland, (NTGA), 1 Parimahana Drive, Kawerau, Auckland, New Zealand New Zealand 2 School of Earth Sciences, Wollega University, 2 Flow State Solutions Ltd., Rotorua, New Zealand Nekemte, Ethiopia

[email protected] 3 Colombian Geothermal Association, Bogotá, Colombia Keywords: Kawerau, wellbore simulator, wellbore modeling, Gudrun, Volsung [email protected]

Ngati Tūwharetoa Geothermal Assets Ltd. Keywords: Microseismicity, Magnitude of (NTGA) relies on real-time wellhead data trends completeness, b-values, Nevado del Ruiz volcano. and periodic downhole wellbore surveys to The Nevado del Ruiz Volcano (NRV) (Colombia) understand and forecast geothermal fluid supply has two areas with geothermal potential located availability and reinjection capacity. This paper to the north and north-west of its crater which illustrates the use of Gudrun, the standalone are highly seismically active. In the period of wellbore simulator application of the Volsung 2000 - 2018 thousands of volcano-tectonic geothermal reservoir simulation software events have been recorded beneath the volcano package. Here we have applied Gudrun for well and within the two geothermal areas, with most performance diagnostics and are using it for earthquakes occuring at depths of 2-9 km and forecasting future well performance based on Md magnitudes up to 4.4. future reservoir conditions. Physical interpretations of subsurface processes Wellbore models were developed for a production related to volcano-geothermal activity can and an injection well from the Kawerau be performed by analyzing microseismicity Geothermal Field, calibrated with wellbore data information (hypocenters and magnitudes). and history-matched with continuous wellhead The frequency-magnitude distribution of data to determine model performance. The earthquakes in any region on Earth can be calibrated wellbore models were used to forecast described by the Gutenberg-Ritcher relationship. well performance using expected reservoir This relationship is linear and from the slope, a and wellhead conditions. The wellbore model common seismological parameter is estimated: forecasts provide insight into well performance the b-value. In the literature, high b-values and reservoir changes and are useful proxies for have been associated with the presence of field performance forecasting while developing magmatic bodies, fluids migration, changes in a full-field numerical reservoir model. Ongoing fluid pressure, and high fracture density. Hence, investigation is also carried out to determine the quantification of b-value and its uncertainty whether mismatches between the wellbore can be associated with the physics of subsurface model forecast and actual wellhead performance mechanisms for earthquakes triggering. The aim could be used as basis for optimising the wellbore of our study is to map b-values (2D and 3D) and downhole monitoring program. delimit its anomalies with implications on the Session 4.1

58 | 42nd New Zealand Geothermal Workshop prospective geothermal areas of Nevado del treatment design, quantification of pre-acidizing Ruiz volcano. Potential mechanisms in the area well parameters and evaluation of acidizing are associated with fluid recharge from rainfall, results. To date, acid stimulation program variable stresses and changes in fluid pressures has been successfully implemented in three due to magma injection and fluid-phase production wells and two injection wells. transition (liquid water-to-vapor transitions). Considerable improvement in production and injection capacities of these wells were attained Session 2.3 that improved the operational level of the power plant in Dieng Geothermal Field. 84 | WELL INTERVENTION AND ENHANCEMENT IN DIENG GEOTHERMAL Session 7.2 FIELD, INDONESIA

Ichwan Agusta Elfajrie1, Stefanus Kusuma Adityawan1, Luthfan Hafizha Judawisastra1, Muhammad Istiawan Nurpratama1, Dodi Herman1 and Ramonchito Cedric M. Malate2

1 PT Geo Dipa Energi (Persero) Aldevco Octagon 2nd Floor, Jl. Warung Jati Barat No. 75, South Jakarta 12740 - Indonesia

2 KDA Consulting Limited, 1 Pepene Avenue, Waiata Shores, Conifer Grove, Auckland 2112, New Zealand [email protected]

Keywords: Dieng, well enhancement, acid stimulation

PT Geo Dipa Energi, (Persero) started developing Dieng Geothermal Field in 2002 and has since implemented operational strategies to sustain steam supply to the installed plant capacity of 60 MWe. Periodically, the company conducted a candidate selection and prioritization of the wells for well workover and enhancement to address steam supply and injection capacity shortfall. The results of evaluation formed the basis in implementing a well intervention and acid stimulation campaign for the prioritized candidate production and injection wells in Dieng Geothermal Field. Improvements were initiated in terms of well testing and analyses and acid treatment design to increase the effectiveness of the well stimulation. The use of electronic pressure-temperature-spinner logs and improved well test interpretation became essential for better candidate selection, acid

23-26 November 2020 | 59 85 | HYDROTHERMAL ALTERATION AND Alteration zones consist of [1] Smectite-Chlorite- FLUID CHARACTERISTICS STUDY OF PANTI Quartz Zone at 0-85 meters depth, [2] Smectite- GEOTHERMAL FIELD, PASAMAN REGENCY, Chlorite-Quartz-Calcite Zone at 85-481 meters WEST SUMATRA, INDONESIA depth, and [3] Illite-Chlorite-Calcite-Quartz-Epidote Zone at 481-534 meters depth. Dissolution and Philbertha Aurelia Wibisono1 and Niniek Rina open-space filling also occurred. Hydrothermal Herdianita2 alteration paragenesis of open-space filling 1 Department of Geological Engineering, Faculty minerals shows that ancient fluid was neutral of Earth Science and Technology, Bandung with 140-160°C then cooled down to 120-130°C. Institute of Technology, Jl. Ganeca 10, 40132, Currently, Panti Hot Springs are neutral, partially Indonesia. equilibrated, sulphate water type, while Ujung Padang and Lundar hot and warm spring are 2 Research Group of Petrology, Volcanology neutral bicarbonate water. Lundar Warm Spring and Geochemistry, Faculty of Earth Science and is partially equilibrated while Ujung Padang Hot Technology, Bandung Institute of Technology, Jl. Springs are immature. There are 3 hydrothermal Ganeca 10, 40132, Indonesia. systems named Panti, Ujung Padang, and Lundar. [email protected] The systems sourced from meteoric water that charged through tectonic fractures, heated up Keywords: Fluid characteristic, geochemistry, by unrevealed intrusion rock, and discharged geothermal, hydrothermal alteration, Panti. as thermal springs towards faults. Panti, Ujung Panti Geothermal Field is being associated with Padang, and Lundar system have permeable zones pull-apart basin at Sumatran Fault System and with temperatures less than 150°C on Granodiorite, Tertiary volcanic activities. This field has seven Granite-Granodiorite, and Slate unit respectively. hot and warm springs with temperatures up to Session 7.2 99°C. A more detailed analysis is needed to get a better understanding of subsurface alteration 86 | APPLYING EGS (ARTIFICIAL WATER and fluid characteristics in Panti geothermal RECHARGE) TO A GEOTHERMAL RESERVOIR field. This research’s goal is to understand the IN JAPAN alteration process and fluid characteristic by determining lithologies, subsurface alteration, Yoshimatsu K1, Ichinohe T1, Okabe T2, Kato M2, Abe and manifestation fluid characteristics. Y3, Yoshie Y3, Asanuma H4 and Okamoto K4

Primary data of a geothermal gradient well core 1 Japan Oil, Gas and Metals National Corporation (PNT-1) with 534 meters depth and manifestation (JOGMEC), 2-10-1 Toranomon, Minato-ku, fluid geochemistry data were used in this Tokyo 105-0001, Japan research. Secondary data of geological and 2 Geothermal Energy Research & Development geophysical reports of the observation field were Co., Ltd. (GERD), 1-22-4 Shinkawa, Chuo-ku, Tokyo used to support the research. Megascopic and 104-0033, Japan microscopic observation, X-Ray Diffraction, fluid inclusion, and water geochemistry analysis were 3 Okuaizu Geothermal Co., Ltd. (OAG), 1034-1 conducted in this research. Yanaizu town, Kawanuma, Fukushima 969-7321, Japan The lithologies of PNT-1 were grouped into Granodiorite, Old Talu Volcanic Product, 4 Fukushima Renewable Energy Institute, Young Talu Volcanic Product, and Alluvial Unit AIST (FREA), 2-2-9 Machiikedai, Koriyama, of Eocene-Holocene age. The intensities of Fukushima 963-0298, Japan alteration from samples are weak to intense. [email protected]

60 | 42nd New Zealand Geothermal Workshop Keywords: EGS, R&D, Water Injection, Artificial 87 | OPPORTUNITIES FOR ELECTRICITY reservoir, Artificial water recharge, Recharging, GENERATION WITH BINARY CYCLE POWER Simulation, Reservoir Management, AE PLANTS IN LUMUT BALAI GEOTHERMAL AREA The power generation output of many Japanese geothermal power plants has been declining Doddy S. Gunawan over time. One of the reasons is the imbalance Pertamina Geothermal Energy, Skyline Building, between their production and the natural 14th Floor, Jl. M.H. Thamrin No. 9 Jakarta, 10340, recharge of meteoric water. To mitigate or Indonesia improve the decline, JOGMEC, an independent administrative agency in Japan, has focused on [email protected] artificial recharge technology, which is classified Keywords: Lumut Balai, Brine, Binary Cycle. as a type of enhanced/engineered geothermal system (EGS). Lumut Balai Geothermal Field is a working area managed by Pertamina Geothermal Energy In 2013, JOGMEC set out a project to apply (PGE) in South Sumatra Province, Indonesia. This the technology to Japan’s geothermal power field has generated 55 MWe of electricity to the plants. The purpose of this project is to establish grid on the Sumatra Island after Lumut Balai appropriate recharge methods for their long Geothermal Power Plant (GPP) Unit-1 achieve the term stable production, including techniques commercial operation date in the first quarter of for predicting and evaluating the effects of 2020. Lumut Balai GPP Unit-2 EPCC project will the EGS (artificial water recharge). To establish follow with 55 MWe capacity in the future. The methods and verify the effectiveness of the two GPP units are turbine condensing power project, recharge tests were carried out in plants. 2017 and 2019 through to early 2020 at the Yanaizu-Nishiyama geothermal power plant Lumut Balai Geothermal Field is a two phase in Fukushima prefecture, of which production field with water predominance (dryness of has been gradually declining. Although some around 20%) where this two phase fluid flow positive effects of the EGS have been confirmed, into the separator to separate dry steam and hot continued recharge and further verification are brine. Dry steam is used to turn turbines and required to establish the appropriate methods generators to produce electricity and hot brine is and prove their effectiveness. injected into the reservoir through a reinjection well. The injected hot brine still has high heat Session 7.3 potential and can be used to generate electricity using a binary cycle power plant.

This paper tries to find out how much electricity is generated from the binary cycle power plant by utilizing hot brine, which may be a binary cycle that can be used as a way to increase the generation capacity in Lumut Balai Field in the future.

Session 7.3

23-26 November 2020 | 61 88 | SIGNIFICANCE AND METHODOLOGY 89 | GEOTHERMAL DEVELOPMENT: A GAME OF GEOTHERMAL RESOURCE POTENTIAL OF CHANCE AND WIT SURVEY IN JAPAN Abd Ghafar S, Goh O, Hoepfinger V, Hunter E, Kotaro Tano, Kazuya Naito, Daisuke Hyodo Jones J, Murphy B and Potter J

Japan Oil, Gas and Metals National Corporation Mercury NZ Ltd, 283 Vaughan Road, Rotorua (JOGMEC), 2-10-1 Toranomon, Minato-ku, 3010, New Zealand Tokyo 105-0001, JAPAN [email protected] [email protected] Keywords: Geothermal development, Keywords: Geothermal, JOGMEC, Resource educational game, diversity, STEM, community Potential Survey, Airborne Geophysical Survey, engagement, WING AGG, HTEM, Heat-flow Drilling, Corling. In order to inspire diverse young people into While Japan is blessed with high geothermal STEM careers, colleagues from Mercury NZ energy potential, many areas remain unsurveyed Ltd partnered with The University of Auckland due to the mountainous landscape of Japan (UoA) Women in Engineering Network (WEN) and the environmental regulation regarding and presented an introduction to geothermal national parks. In these areas, Japan Oil, Gas development to high school aged youth during and Metals National Corporation (JOGMEC) Enginuity Day 2019. Beyond typical methods of conducts airborne geophysical surveys (gravity, industry presentation to students, the Mercury electromagnetic, magnetic) and heat-flow drilling team decided to create an interactive game to surveys in order to understand the geological foster engagement and learning. structure. The data obtained through these The sequence of the game leads players surveys is provided to geothermal resource through the entire process from exploration developers as well as local governments in to commercial development of an unexplored order to reduce exploration risks and promote geothermal resource. In the first stage, their further survey for geothermal resource participants are provided maps and geoscience development. data, which they analyse to select well In addition to these surveys, from this year, locations. In the second stage, they discover the JOGMEC starts implementing surface geophysical productivity and enthalpy of their new wells. surveys (gravity, magnetotelluric) and deeper Penultimately, using well data and information drilling survey for identifying geothermal fluids about the efficiency of various power plant types, in order to acquire more detailed subsurface they place a fictional power plant and design information. By conducting these surveys, pipelines to connect their wells. Finally, the game JOGMEC hope to reduce the exploration risk and is scored by translating the production of their contribute to the further geothermal resource powerplant and wells drilled into an economic development. output.

Session 7.2 To simulate the unpredictable reality of geothermal development, chance cards are allocated at multiple stages with varying degrees of financial setback.

The reception to the game was overwhelmingly positive. While it was designed specifically to introduce high school aged women to the

62 | 42nd New Zealand Geothermal Workshop geothermal industry, a similar style of game injected over the pressure required to inject it. could be adapted to engage other ages or to Injectivity is known to vary with temperature of focus on other topics. injection fluid and rock formation.

Session 6.2 Two of the injection wells at Ngatamariki are presented in this work: NM08 and NM09. The 90 | INJECTIVITY CHANGES AT NGATAMARIKI injectivity indexes for these wells are determined downhole and incorporates fluid density Jamie Potter, Aimee Calibugan, Alan Ferguson, changes, friction losses along the wellbore, and and George Allan changes in reservoir pressure. In the first few Mercury NZ, 283 Vaughan Rd, Rotorua, years of operation after drilling, a large increase in New Zealand injectivity index has been observed in both wells. In recent years the injectivity has declined overall. [email protected] Additionally, and investigated here, a varying rate Keywords: Ngatamariki, Taupo Volcanic of decline in injectivity index has been observed Zone, injection, injectivity index, temperature, recently. The temperature of the reinjection microseismicity brine varies up to 10°C. The correlation between the difference in injectivity index in NM08 and Ngatamariki geothermal system in the Taupo NM09 and change in injection temperature Volcanic Zone of New Zealand generates power is examined. The correlation between the from an 82 MWe binary power station. All the difference in injectivity index and microseismicity produced geothermal fluid is reinjected into four is also investigated. Uncertainties in determining injection wells minus minor losses of around 2%. injectivity index are explored. The reasons for Wellhead pressures, flow rates, and injectivity of injection variation are not fully understood and Ngatamariki reinjection wells have varied over warrant further investigation. the 7 years of operation. The injectivity index of a well is determined from the amount of fluid Session 4.1

TOGETHER, WELL AHEAD Moving the Geothermal Industry Forward

23-26 November 2020 | 63 91 | A NON-PRODUCTIVE TIME ANALYSIS carried out around 25 years ago. However, FROM GEOTHERMAL DRILLING CAMPAIGN the drilling activity report and data were not IN WEST JAVA TO IMPROVE FUTURE documented and processed properly. Therefore, DRILLING PLANNING when a drilling campaign expansion is about to commence, the scattered and unprocessed Annisa Rachmadani1, Riviani Kusumawardani1, drilling records make it difficult to create Githa Putri Rizkiani2, Reifandi Redhiza3, offset well analysis. This will cause the drilling Didin Chaerudin Irwansyah4, Ketut Darmana engineering and planning are not as straight- Yasa⁵, Sahat Nainggolan⁶ and Nanang Fathur forward, because the engineer has to sort, Rozi⁷ cleanse, and processed the data first before 1 PT Rigsis Energi Indonesia, Equity Tower 49th being able to generate analysis. floor, Sudirman Rd. 52-53, South Jakarta, Jakarta, This paper aims to demonstrate the offset well Indonesia analysis from the drilling operation perspective. 2 Institut Teknologi Bandung, Ganesha St. 10, An overview of daily drilling report processing Bandung, West Java, Indonesia into a usable information for drilling planning is discussed. The NPT contributors incurred during 3 Universitas Pertamina, Teuku Nyak Arief Street, first drilling campaign 25 years ago are identified South Jakarta, DKI Jakarta, Indonesia and analyzed. The NPT analysis then can be used 4 PEM Akamigas, Gajah Mada Street 38, Cepu, to assist the drilling planning with the final goal Blora, Central Java to improve future drilling planning process and to potentially save cost by mitigating the most 5 Professional Drilling Consultant, Bali, Indonesia possible problems to occur in the field. 6 Professional Drilling Consultant, Bintaro, Session 8.2 Banten, Indonesia

7 Professional Drilling Consultan, Depok, West 92 | DRILLING ACTIVITIES AND PARAMETERS Java, Indonesia ANALYSIS TO OPTIMIZE STUCK PIPE PREVENTION IN A GEOTHERMAL FIELD [email protected] Astrini Yuswandari1, Dimas Maulana1, Keywords: Geothermal, Indonesia, drilling, non- Dorman Purba2 and Daniel Adityatama2 productive time, offset well analysis. 1 Bandung Institute of Technology, Bandung, Drilling is one of the most cost-intensive Indonesia activities in a geothermal project. The longer it takes to drill a well, the more expensive the well 2 PT Rigsis Energi Indonesia, Jakarta Selatan, becomes. It is therefore important to optimize Indonesia the time spent in drilling to optimize the cost of [email protected] a well. The occurrence of an unplanned event that might prolong the drilling operation can Keywords: geothermal, drilling, non-productive be classified as Non-Productive Time (NPT), and time, stuck pipe this period will contribute to the cost overrun Geothermal drilling has been an issue with its of the well. Understanding the major NPT high cost taking up to fourty-percent of total happened in a drilling campaign and extracting field development cost. This high cost can lessons learned out of it, is hence crucial for still increase significant amount caused by improvement in the future drilling campaign. the long duration of geothermal drilling due A drilling campaign for a vapor-dominated to non-productive time. The long duration geothermal field in West Java, Indonesia, was for non-productive time represents problems

64 | 42nd New Zealand Geothermal Workshop encountered in geothermal well drilling. One Geothermal energy is expected as one of of the most frequent problems is the stuck the renewable energies against the global pipe, a condition whereby the drill string warning, which we have to overcome in this cannot be pulled or moved. Generally, the stuck century. However, the conventional geothermal pipe is classified into differential sticking and development that pumps up and uses the mechanical sticking. subsurface hot water has not been much promoted because of the objection of the local residents. This study is analyzing the occurrence of stuck The Hot Dry Rock (HDR) method, which does not pipe empirically with qualitative and quantitative pump up underground hot water, was studied but analysis. The analysis is done through offset- suspended by economical and other reasons. well data consists of drilling activities and drilling parameters. The drilling activities cover The HDR technology creates an artificial reservoir the duration of productive time and non- by hydraulic fracturing at the area where natural productive time, including activities before and geothermal system is not or poorly developed, during the stuck pipe. Meanwhile, the drilling and pressurises water into the reservoir to extract parameters consist of torque, standpipe pressure, subsurface heat. Several demerits have been rate of penetrations, revolution per minute, pointed out such as the outflow of water from pumping rate, well inclination not to mention the reservoir, and the low temperature due to the lithological data from formation evaluation log. bypass of injected water (Short Circuit). The induced The objectives of this study are to determine earthquake during the hydraulic fracturing and the the wells with stuck pipe occurrence, most water circulation is another matter of concern. troublesome depth intervals, possible type Carbon dioxide (CO2) in the supercritical condition and cause of sticking, parameters cut-off and (ScCO2) has better thermal properties as the heat patterns, and also lithology type with most transport fluid than water. ScCO2 inhibits the frequent stuck pipe occurrence. This study dissolution from host rocks and the sedimentation also includes the challenges in analyzing the of minerals in the fractures. Large buoyancy can available drilling data of this field. In results, all be expected to reduce the pumping energy. Also, possible stuck pipe were mechanical sticking ScCO2 can penetrate into narrow micro-cracks due and occurring in Andesites-dominated rocks to its small viscosity. An output of about 1.5 times located in high-temperature reservoir zone with that of water can be expected with use of ScCO2 as no exact drilling parameters cut-off and patterns a working fluid. are found. ScCO2 that migrates from the flow path would be Session 8.3 expected to be sequestered and fixed as carbonate minerals in HDR. In addition, the formation of 94 | UTILISATION AND SEQUESTRATION OF the Short Circuit and the scale production might SUPERCRITICAL CARBON DIOXIDE IN THE be overcome by controlling CO2. The induced GEOTHERMAL FIELD earthquakes at the reservoir creation can be also Toshiyuki Tosha and Toshiki Ozaki suppressed by using CO2 as a fracturing fluid. There are many advantages in use of CO2 but are also Geothermal Unit, Japan Oil Gas and Metals many subjects to be solved. We will progress a new National Corporation (JOGMEC) geothermal research program using CO2. In this 2-10-1 Toranomon, Minato, 1050001, JAPAN paper, subjects on the use of CO2 in the geothermal [email protected] field and the processes to the implementation will be discussed. Keywords: Hot Dry Rock, Global warming, CO2, Sequestration, Utilisation Session 7.3

23-26 November 2020 | 65 96 | SIMULATING EFFECT OF INSULATED 97 | DOUBLE ENERGY INPUT, A PROPOSAL DRILLPIPE ON DOWNHOLE TEMPERATURE FOR A NOVEL SOURCE OF ELECTRICAL IN SUPERCRITICAL GEOTHERMAL WELL ENERGY DRILLING Daniel Ramirez Ordás1,2 Ryo Ando and Shigemi Naganawa 1 University of Auckland, New Zealand Graduate School of International Resource 2 Universidad de Monterrey, Mexico Sciences, Akita University, 1-1 Tegata- Gakuenmachi, Akita, 010-8502, Japan [email protected]

[email protected] Keywords: DEI, Double Energy Input, Hydroelectrical, Seawater, Open Pit Mine, Keywords: supercritical geothermal well drilling, Geothermal, Supercharging, novel source of down-hole cooling, mud circulation, insulated electrical energy, Sonora, Guaymas, Mexico drill pipe, numerical simulation renewables production. A research and development project on In order to slow down adverse global supercritical geothermal power generation anthropogenic effects such as global climate technology, in which the exploratory drilling change and the destruction of ecosystems, project is known as the Japan Beyond-Brittle alternative energy sources that are clean, Project (JBBP), is in progress in Japan. To design renewable, and efficient are needed to replace the first exploration well, which is planned the existing energy sources. to be drilled in a few years, we are studying a down-hole cooling strategy by mud circulation Double Energy Input is a novel invention that during drilling, casing running, cementing and gathers two renewable energy resources: hydro- completion operations. Because the drilling site electrical power and geothermal power. This is not yet determined, numerical simulations invention utilises the sea as its reservoir, the dam were conducted for subsurface conditions based is a wall of a big pit hole, and in the base of such on the Kakkonda WD-1a well, the world first pit, we will use the geothermal power for ridding super-hot geothermal well over 500°C previously off the water. drilled in Japan. This model is designed to generate between In this study, we focused on the effect of 1,200 – 1,500 MW of power in the hydro- insulated drill pipe on down-hole temperature electrical phase and will generate about 4.86 during drilling with drilling fluid circulation. It was tons of salt per second. An additional 800 MW of found that the combination or configuration of energy will be produced by supercharging the insulated and normal drill pipes had considerable hot water at the bottom with heat and pressure influences on the down-hole temperature and running a vapour power plant. profiles as well as the thermal performance of This model provides an alternative means for insulated drill pipe itself. The optimum insulated producing clean and renewable energy with two drill pipe configuration and drilling operation abundant resources, sea-water and geothermal condition are discussed based on the results of heat. the numerical simulation studies. Session 3.1 Session 7.2

66 | 42nd New Zealand Geothermal Workshop 98 | DRILL BITS SELECTION ANALYSIS IN this tool is to crush or cut the rock. Unfortunately, NON-CONSIGNMENT PROCUREMENT the selection of the best available bit for a job ARRANGEMENT IN GEOTHERMAL DRILLING can be determined only by trial and error. This PROJECT is because bit selection refers to several factors, such as the formations and drilling parameters. In Riviani Kusumawardani1, Dicky Alamsyah1, non-consignment procurement arrangements, Paul Asaari2, Andri Burnama3, drill bit selection shall be completed prior to the Ketut Darmana Yasa4 execution. 1 PT Rigsis Energi Indonesia, Equity Tower 49th This paper explores the selection workflow floor, Jakarta, Indonesia and assumptions used in selecting drill bits for 2 Professional Drilling Consultant, Jakarta, geothermal operation based on offset well and Indonesia recent market reviews. Discussion covers drilling bit specifications and quantity determination 3 DSV Consultant, Balikpapan, Indonesia for 3 wells in a drilling campaign. The results are 4 Professional Drilling Consultant, Bali, Indonesia recommendations for preferred drill bit selection in non- consignment procurement arrangement. [email protected] Important data that must be recorded during Keywords: drill bits, drilling procurement, drilling is also mentioned in the discussion. This is geothermal drilling. critical for drill bit selection optimization in future campaigns. The drill bit is one of the most important tools in geothermal drilling operations. The main role of Session 7.2

23-26 November 2020 | 67 99 | WELLTEC COMPLETION SOLUTIONS a positive confirmation of the WAB being set, METAL EXPANDABLE PACKER AND 2ND the cementing operation of the annulus was STAGE CEMENTING FOR GEOTHERMAL WELL completed in the fully controllable annular RE-LINING volume ensuring 100% cement coverage. As a redundancy in case trapped water should occur, Kyle Ivar Jamieson1, Espen Dalland1 and multiple burst discs have been integrated in Genevieve Cherube Carlos2 the WAB to avoid potential casing collapse or 1 Welltec A/S Unit 21-1, deformation. Level 21 Menara Prestige, 1 Jalan Pinang, As a result, the client could put the well back MY-50450 Malaysia on production with full integrity, albeit with a 2 EDC (Energy Development Corporation) slightly reduced wellbore diameter. 40th Floor One Corporate Centre, Novel/Additive Information Julia Vargas Corner Meralco Avenue, Welltec’s WAB metal expandable packer Ortigas Centre, Pasig City 1605, Philippines minimizes completion and workover risks [email protected] [email protected] through quick and simple isolation of the [email protected] integrity issues, capable of offering high temperature metal to metal sealing whilst EDC (Energy Development Corporation) in the ensuring a life of well product. Philippines faced integrity issues in 3 wells due to casing corrosion and collapse with the 9-5/8” Session 7.2 and 13-3/8” casing on a geothermal well and was required to re-line with 7” and 9-5/8” casing with 101 | SIMULATING INTERFERENCE EFFECT a metal expandable packer WAB (Welltec Annular BETWEEN REINJECTION WELLS Barrier) to reinstate integrity of the 9-5/8” and 13- Marastio, F. E., Hastriansyah, G., Saputra, M. B., 3/8” casing. This paper will discuss an operation Arifin, M. T., Pasaribu, F., and Silaban, M. S. P. in which the new 7” and 9-5/8” casing was deployed and set inside 9-5/8” and 13-3/8” casing PT. Pertamina Geothermal Energy, Skyline using an 812WAB and 1214WAB in conjunction Building 19th Floor, Jakarta, Indonesia with 2nd Stage Cementing Collar. [email protected] Results, Observations, Conclusions Keywords: Interference, Transient, Injection Well, The WAB and 2nd Stage Cementing Port Collar Injection Capacity. was deployed to setting depth and cementing tool consisting of two cups style packers and Ensuring the performance of reinjection wells is an injection port positioned in-between was important for the sustainability of geothermal used for both setting/expanding the WAB. Then, field management. One of the problems that is opening the cement collar and performing rarely noticed in the reinjection performance is the cementing operation and subsequently the interference-effect. The interference-effect closing the cement collar, all in the same run. could cause a significant drop in injection well The fluid level was below the setting depth, so capacity. the equipment was installed in a “dry” well and Two reinjection wells were suspected of throughout the operation continuous cooling having interconnected fracture permeability was performed by pumping water down into and bounded reservoir. Although the distance the well. between the feed zone is more than 300 meters, By establishing returns to surface after Well D-2 experienced a temperature drop and opening the stage collar we were able to get pressure increase during the Injectivity Test of

68 | 42nd New Zealand Geothermal Workshop Well D-3. A method to estimate optimum total with the liquid phase in each stage; it is present reinjection capacity is delivered. in steam lines due to minor amounts of brine carryover. The approach is using the nodal analysis to obtain each wells’ reinjection capacity. Then, The removal of slightly volatile silica can also analytical and semi-numerical transient models be accounted for. Heat loss from pipelines are used to obtain reservoir properties also to can produce significant amounts of steam simulate the optimum reinjection capacity due condensate which is involved in solution/mixing to the interference-effect. within each stage. If the condensation can be reasonably estimated in any section, then it Session 7.3 can be used as a dilution-tracer to calculate the purity of the total steam flow in that section. 103 | GEOTHERMAL STEAM PURITY MODELLING – THEORY AND PRACTICE Assumptions about turbulent mixing of steam and brine/condensate and attainment of Tracy D Mills and Brian G Lovelock chemical equilibrium in each stage are explained, Jacobs New Zealand Ltd, along with guidance on acceptable scrubbing 12-16 Nicholls Lane, Parnell. velocity criteria, and the effectiveness of P O Box 9806, Newmarket, Auckland, condensate removal at drop pots. New Zealand Insights that may be gained from steam purity [email protected] modelling are discussed, and “proof” of the validity of modelling is provided by comparing Keywords: Geothermal steam purity, modelling, modelling predictions with generalised (i.e. non- chloride ion, silica, silica distribution. specific) geothermal steam system data. Geothermal steam purity modelling is Session 5.2 considered by some to be an esoteric exercise. Two experienced practitioners in geothermal process engineering and geothermal chemistry seek to demystify steam purity modelling for the next generation of practitioners. This is done by explaining the basic principles used (along with key assumptions) and how modelling can assist steam separation and scrubbing pipeline design. Verified by drain-pot sampling, it provides an accurate measure of the overall efficiency of steam line scrubbing and gives confidence in the level of steam purity at the turbine – a key parameter operators are interested in.

Steam purity modelling considers initial steam separation performance and quantifies heat and mass transfer within steam lines in discrete stages, corresponding to each successive condensate removal point as well as final demisting prior to admission to the power plant. Chloride ion is a representative dissolved impurity that is non-volatile and remains entirely

23-26 November 2020 | 69 104 | COVID-19’S IMPACTS ON GEOTHERMAL geothermal drilling projects. Thus, the presence DRILLING PROJECTS IN INDONESIA of this paper intends to fill the gap in the field.

Fikha Fininda1, Vicki Agustino1, Session 7.3 Farhan Muhammad1 and Paul Asaari2 105 | INVESTING IN EXPLORATION 1 PT Rigsis Energi Indonesia, Equity Tower 49th GEOSCIENCE AND INNOVATION: A Floor, SCBD, Jakarta, Indonesia GIS-BASED GEOTHERMAL RESOURCE 2 PT Supreme Energy, Menara Sentraraya 23rd PRIORITISATION TOOL FOR TOHOKU Floor, Jl. Iskandarsyah Raya No. 1A, Jakarta, REGION, JAPAN Indonesia Greg Bignall1, Samantha Alcaraz2, Kento Nakao3 [email protected] and Hugh O’Keeffe3

Keywords: COVID-19, geothermal, drilling, 1 Baseload Capital Sweden AB / Baseload Power Indonesia. New Zealand Limited, Taupo, New Zealand

The Corona Virus (COVID-19) pandemic has 2 GNS Science. Wairakei Research Centre, Taupo, spread rapidly to more than 200 countries New Zealand around the world. This does not only raise 3 Baseload Power Japan, Tokyo, Japan challenges towards public health but also agitates other sectors, including the energy [email protected], industry. The economic slowdown and [email protected], quarantine practices contribute to large impacts [email protected], on the energy sector, including geothermal. [email protected]

The continued impact of the COVID-19 Keywords: GIS, Automation, Geospatial Data, pandemic is clearly seen in the movement Geothermal Resource Prioritization, Tohoku, restrictions by most governments around the Japan. world, including in Indonesia. Thus, this will We have designed, built and are now utilising inevitably cause the geothermal sector to a GIS-based geothermal resource prioritisation experience more postponed projects. tool for the Tohoku region, Northern Japan. For Drilling is one of the biggest cost contributors the first time, we have a toolbox for automating to build a geothermal power station with up the integration of large, scientifically diverse, to 34% of the total project cost. Identifying the multi-sourced public and institutional geospatial market price for drilling material and services is datasets, that support Baseload Power’s very important. It will allow us to get information geothermal resource prospectivity assessment about the market status to calculate the total process. We assign weighted numerical values well cost. However, the market survey that has to resource, infrastructure and development been conducted in 2019 might differ from the variables aiding identification of geothermal current actual price due to COVID-19’s impact. systems, many overlooked for more than onsen Therefore, it will affect the geothermal project bathing, with attributes for scaled, modular plant cost in total. electric power and community-driven direct use applications. This paper aims at discussing how the COVID-19 pandemic will impact the current geothermal The Tohoku region of northern Honshu drilling cost and the latest market survey boasts several hundred hot spring areas, but in Indonesia. There has been very limited geothermal development has been hindered research of COVID-19’s impact on the Indonesia by community concerns, limited grid availability

70 | 42nd New Zealand Geothermal Workshop and uncertainties regarding development 106 | STUCK PIPE FREEING PROBABILITY potential and resource viability, despite a large OF SUCCESS IN GEOTHERMAL DRILLING volume of historical and recent surface surveys OPERATION: A CASE STUDY IN JAVA and subsurface geoscience (including well Dicky Alamsyah1, Daniel Adityatama1, data). Our approach facilitates integration of the various datasets, which can be visually presented Adi Krishamidan2, Andri Burnama2, in an unbiased assessment or as generated Ketut Darmana Yasa2, Nanang Fathur Rozi2 resource favourability scenarios. This provides 1 PT. Rigsis Energi Indonesia, Equity Tower, Baseload Power with a unique advantage to 49th Floor, Jakarta Selatan, Indonesia identify geothermal areas of interest, initiate an appropriate exploration strategy, and 2 Professional Drilling Consultant, Indonesia engage with individuals, communities, industry [email protected] collaborators and regulators early in the project management process, in order to meld Keywords: stuck pipe, stuck pipe freeing, appropriate (ORC, binary or other) technologies, geothermal, geothermal drilling, probability of our commercial goals, and the aspirations of local success, Indonesia. and development partners. Stuck pipe is a common problem in geothermal Session 1.3 drilling operations. Stuck pipe can lead to extra cost due to lost-in-hole tools, sidetrack, fishing operation, and cost due to prolonged total drilling operation/campaign. The commonly faced dilemma in mitigating stuck pipe is to decide whether to continue with the attempts to free the pipe or cut the pipe or sidetrack the well. One of the consideration factors for the issue is to calculate the probability of freeing the pipe.

The purpose of this study is to investigate the connection between the probabilities of success with stuck pipe freeing attempts. Using statistical analysis, the study analysed the events of stuck pipe from a drilling campaign in Java in the 1990s. This study finds out that the answer to previously unknown effective time of work pipe operations. Further studies are needed to establish the relationships of drilling parameters to the probability of success and develop a cost- effective preventive/corrective measure to stuck pipe problem.

Session 5.1

23-26 November 2020 | 71 107 | DISCRETE VS INTEGRATED PROJECT This paper is expected to give a thorough MANAGEMENT (IPM) AND INTEGRATED summary of the advantages and disadvantages DRILLING SERVICE (IDS) CONTRACT FOR of discrete and IPM/IDS contract types for GEOTHERMAL DRILLING IN INDONESIA geothermal drilling campaigns. What type of contract is most suitable for geothermal Vicki Agustino1, Farhan Muhammad1, operators based on the resources they have Fikha Fininda1, Daniel Adityatama1, and the kind of project that they want to Adi Krishamidan2, Paul Asaari2, develop? Further studies with more sources are Sahat Nainggolan2 still required to fully prove the feasibility of the concept. 1 PT. Rigsis Energi Indonesia, Equity Tower, 49th Floor, Jakarta Selatan, Indonesia Session 8.2

2 Professional Drilling Consultant, Jakarta, 111 | CHALLENGES IN PROVIDING A Indonesia RELIABLE WATER DISTRIBUTION SYSTEM *[email protected] FOR GEOTHERMAL DRILLING OPERATION IN INDONESIA Keywords: Geothermal, Drilling, Contract, Indonesia Daniel W. Adityatama1, Dorman Purba1,2, Vicki Agustino1, Annisa Rachmadani1, Hafni Wiharlan1 Drilling for geothermal activity in Indonesia and Kathlyn K. Pasmeputra1 has been growing in recent years. Many energy companies have entered the geothermal 1 Rigsis Energi Indonesia, Equity Tower, 49th industry in Indonesia. These newly established Floor, SCBD, Jakarta companies usually have limited geothermal 2 Enerka Bhumi Pratama, KKO Cilandak Gudang knowledge on their team. Most of them use 401, Jakarta Integrated Project Management (IPM) and Integrated Drilling Service (IDS) contract types [email protected] to develop their geothermal area starting from Keywords: geothermal, drilling, Indonesia, the drilling campaign to their power plant exploration, water supply, water transfer, purchasing and installation. Unlike geothermal infrastructure, local community. practices, the oil and gas industry in Indonesia is more mature and settled, where most of Geothermal drilling activities, both in the operators are using a discrete type of contract exploration and development stage, require a for drilling. significant amount of fresh water supply. The water consumption generally increases during The purpose of this study is to compare between drilling into the reservoir zone, which consists the discrete contract type and IPM/IDS contract of fractures and faults allowing higher chance type. Various aspects like company strategy, of lost circulation event. Continuous water resources quantity and quality, logistic and supply with sufficient flow rate, to be circulated location of the project and many other things into the hole, is very critical during drilling will give us insight into what is the most suitable because it serves many purposes. When the drilling contract type between IPM/IDS or water distribution into the well is interrupted discrete for geothermal companies in Indonesia. or stopped completely, drilling activity must This application of contracts is analyzed based be ceased to avoid any potential downhole on the technical and economic aspects to give a problem due to lack of water or mud circulation. summary of what factors need to be considered Unfortunately, in Indonesia, providing fresh before applying one type of contract. water for drilling operation is often not an easy

72 | 42nd New Zealand Geothermal Workshop task. Most geothermal prospects in Indonesia of computational cost. Furthermore, decision- are located in fertile mountainous areas that makers typically desire the quantification of have low rainfall and are inhabited by people, uncertainty and confidence in any calibration thus the available sources of fresh water are results. These problems have been addressed often used for irrigating rice fields. This condition quite successfully in related fields, such as forces geothermal developers to use other petroleum engineering, by using so-called water sources with low (acidic) pH that often ensemble-based uncertainty quantification located far from the existing road. Additionally, methods. the surface contour from the water source to the Ensemble-based methods use a small collection drilling pad is often extremely uneven. (ensemble) of models, with each ensemble This paper discusses various potential challenges, member having different values for the model both technical and non-technical, in securing parameters (such as deep mass and heat sources fresh water supply for geothermal drilling or subsurface permeabilities). The associated operations in Indonesia. Several solutions or calibration methods guide this ensemble mitigations based on literature studies and of different models to regions in parameter authors experience are also summarized in this space which provide adequate matches to study. the measured field data, while ensuring an appropriate diversity of models to characterise Session 5.1 uncertainty. In the Bayesian framework, ideally, the distribution of the ensemble should 116 | REPRESENTATION OF UNKNOWN converge to the posterior probability distribution PARAMETERS IN GEOTHERMAL MODEL representing this uncertainty, i.e., the probability CALIBRATION distribution of the unknown parameters given Ruanui Nicholson1, Oliver J. Maclaren1, John P. the measured field data. O’Sullivan1, Michael J. O’Sullivan1, Anna Suzuki2 Session 1.2 and Elvar K. Bjarkason2

1 Department of Engineering Science, The University of Auckland, Auckland 1142, New Zealand

2 Institute of Fluid Science, Tohoku University, Sendai, Japan [email protected]

Keywords: Geothermal model calibration, uncertainty quantification, ensemble-based methods, parameterisation, reservoir modelling.

Computational reservoir models are commonly used to inform management decisions in the geothermal energy sector. With a well- calibrated model, a range of future scenarios can be simulated and informed decisions can be made. However, the task of calibrating large-scale geothermal models is challenging, both from a conceptual standpoint and in terms

23-26 November 2020 | 73 117 | AN INTRODUCTION TO OPTIMAL DATA uncertainty in the parameters after conditioning COLLECTION FOR GEOPHYSICAL MODEL on the field data. This uncertainty can then CALIBRATION PROBLEMS help guide the management of geophysical resources, where, intuitively, reducing (posterior) Ruanui Nicholson, Henry Alferink, uncertainty enables higher quality decisions to Elliot Paton-Simpson1 Michael Gravatt, be made. Susana Guzman, Joris Popineau, John P. O’Sullivan, Michael J. O’Sullivan, Reduction in posterior uncertainty is achievable Oliver J. Maclaren by a) improving measurement precision at existing locations and hence obtaining similar Department of Engineering Science, The data with lower noise or b) collecting additional University of Auckland, Auckland 1142, New data at new locations. Here we focus on the Zealand second option. The cost of collecting data in new [email protected] areas can be considerable, however, especially when this data requires e.g. drilling a new Keywords: Calibration, estimation, inversion, observation well or constructing and deploying Bayesian, data collection, optimization, other expensive measurement equipment. uncertainty quantification, uncertainty Hence, we consider the design problem of how reduction. to determine the reward, in terms of uncertainty Computational modelling and calibration can reduction, of a potential new observation, before play a vital role in various geophysical settings, collection. including the management of geothermal In addition to illustrating the basic principles of reservoirs. The calibration process typically optimal data collection and data worth analysis involves perturbing model parameters, such as using simple geophysical problems, we also subsurface permeabilities, so that the resulting show how the methodology used can be further simulator outputs match field data, usually developed to include, for example, the possibility consisting of noisy surface or subsurface of spatially heterogeneous costs of acquiring measurements. In an engineering context, new data. however, model calibration is not a once-off process, but rather an on-going process that Session 3.2 often requires careful decision-making about whether to collect new measurements and where these should be collected. Here we present a tutorial-style introduction on how to formulate and solve such decision problems, using two archetypal but straightforward geophysical model problems.

The basic calibration problem can be considered a statistical inference problem. In particular, the Bayesian framework for calibration naturally allows for uncertainties in the data, the parameters, and models to be quantified and incorporated into this process. In this framework, the solution to the calibration (and inference problem) is a so-called posterior probability density, which characterises the remaining

74 | 42nd New Zealand Geothermal Workshop 121 | CHARACTERIZATION OF HULULAIS 122 | FEED ZONE EVALUATION IN HULULAIS SUBSURFACE ROCK FORMATION AND ITS GEOTHERMAL FIELD, BENGKULU, IMPLICATION TO STRATO VOLCANO FACIES INDONESIA MODEL HULULAIS GEOTHERMAL FIELD, Muhammad Tajul Arifin, Sapto Trianggo Nurseto, INDONESIA Vivi Dewi Mardiana Nusantara, Graniko Reza Vivi Dewi Mardiana Nusantara, Graniko Reza Pratama, Fadiel Evan Marastio, Mochamad Husni Pratama, Sapto Trianggo Nurseto, Muhammad Thamrin Tajul Arifin and Mochamad Husni Thamrin. PT. Pertamina Geothermal Energy, Menara PT. Pertamina Geothermal Energy, Skyline Cakrawala 19th floor, Jl. M. H. Thamrin No.9, DKI Building 19th floor, Jl. M. H. Thamrin No.9, Jakarta, Indonesia 10430 Jakarta, 10340, Indonesia [email protected] [email protected] Keywords: Hululais, feed zone, permeability, feed Keywords: Hululais, rock formation, zone characterization, feed zone evaluation stratovolcano. Hululais geothermal field is situated within an Hululais geothermal field is located in Lebong overlapping area between the Musi and Ketahun district, Bengkulu province, Sumatera island, Segment. These segments are part of the NW-SE Indonesia. As one of the exploration field Sumatra Fault Zone. These NW-SE structures and operated by Pertamina Geothermal Energy (PGE), also its local lithological factor is hypothesized Hululais geothermal field targeted to generate to influence the permeability of feed zone in 2 x 55 MW electricity by the end of 2020. 24 Hululais by certain degree. wells have been drilled since 2010. Retrieved Drilling campaign in Hululais has been started cutting and cores from the drilling wells are the in December 2010, this activity provides primary data for subsurface modeling. Thus, its subsurface data such as rock cuttings and cores, identification and characterization is important drilling parameters, borehole logging, and for the next field development scenario. completion test data. Spinner data, temperature An updated new subsurface rock formation is measurement, loss circulation while drilling, rate successfully established. They are identified as of penetration, weight on bit, cuttings, cores, Upper Suban Agung Volcanic (USAV), Lower interpreted fracture from borehole logging Suban Agung Volcanic (LSAV), Hululais Volcanic is integrated and analyzed to evaluate and (HV), Hululais Granodiorite Intrusions (HGI), characterize the feed zone of the wells. and Seblat Metasediment (SM). Its unique The study depicts that the feed zone distribution characters and its huge implications for the field and also its permeability is quite unique which development scenario will be explained in this is influenced both by structure and lithological paper. The knowledge to identify these rock factor. The feed zones can be divided into three formations will increase success ratio of well groups based on their vicinity to the surrounding drilling, and reduce potential hazard and loss. structure and their lithological factor. This Poster grouping also correlates with its permeability from high to low. Identifying factors that control the distribution and the permeability of the feed zones will reduce the subsurface uncertainty for well targeting in the future field development.

Session 8.3

23-26 November 2020 | 75 123 | THE ROLE OF THERMAL STRESS IN 124 | A NEW NUMERICAL MODEL OF ENHANCING THE RESERVOIR PROPERTIES THERMAL APERTURE CHANGES IN AN OF ENHANCED GEOTHERMAL ENHANCED GEOTHERMAL SYSTEM RESERVOIR Musa D Aliyu, Rosalind A Archer Musa D Aliyu, Rosalind A Archer Department of Engineering Science, the University of Auckland, Private Bag 92019, Department of Engineering Science, the University Auckland 1142, New Zealand. of Auckland, Private Bag 92019, Auckland 1142, New Zealand. [email protected] [email protected] [email protected] [email protected] Keywords: Induced thermal stress, thermal shock, EGS reservoir, multifracture, horizontal wellbores. Keywords: Thermal aperture, hydro-mechanical aperture, combined aperture, EGS reservoir, THM The injection of cold fluid into a hot dry rock simulation. (HDR) formation causes temperature changes that often induce thermal stress. This will alter Extraction of energy from deep crystalline the reservoir properties of the rock mass and formation requires pressurisation of the rock the fluid, making thermal stress central to mass to create new or enhance existing natural understanding the behaviour of HDR geothermal fractures. The fractures generate a pathway for reservoirs. In order to explore the effect of transport of the fluid and heat back to the surface thermal stress on reservoir properties, this paper for optimum energy production. However, the presents a new numerical model of an enhanced complexity of fracture aperture opening and geothermal system (EGS) using a coupled closure during exploitation has posed a challenge thermo-hydro-mechanical (THM) model. Nine for both engineers and geologists. The most reservoir properties are examined: permeability, widely used model for fracture aperture changes aperture, stiffness, pore pressure, effective stress, is frequently limited to the hydro-mechanical shear stress, density, viscosity, and temperature. effect only. This paper presents a new model The results show that thermal stress enhances that incorporates a complete cycle of thermal, each of these properties substantially when hydraulic and mechanical aperture changes in compared with a model without thermal stress. It an enhanced geothermal system (EGS) reservoir is clear from the simulation that exclusion of the using a coupled thermo-hydro-mechanical thermal stress effect in a model could end in an (THM) simulator. The goal is to understand the erroneous description of the system output. extent to which thermal aperture changes might enhance the performance of EGS reservoirs. Session 1.2 Three reservoir cases are developed: a model of hydro-mechanical aperture changes with a constant thermal aperture; a model of thermal aperture changes employing a constant hydro- mechanical aperture; and a combined model of both hydro-mechanical and thermal aperture changes. The outcomes show that the changes are greater with the thermal aperture than with the hydro-mechanical aperture due to the impact of thermal contraction.

Session 1.2

76 | 42nd New Zealand Geothermal Workshop MB Century is one of the largest energy service specialists in the Asia Pacific region. We have a long history of providing world leading, innovative service to the energy sector, employing over 150 people. We provide award winning services to the oil & gas, and renewable energy sectors in New Zealand, Australia and South East Asia.

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Contact: www.mbcentury.co.nz or [email protected] 23-26 November 2020 | 77 126 | GEOLOGY FAULT NETWORK OF 127 | VOLCANOSTRATIGRAPHY OF HULULAIS GEOTHERMAL SYSTEM, HULULAIS GEOTHERMAL FIELD, BENGKULU, BENGKULU, INDONESIA INDONESIA

Sapto Trianggo Nurseto, Muhammad Tajul Arifin, Graniko Reza Pratama, Vivi Dewi Mardiana Graniko Reza Pratama, Vivi Dewi Nusantara, Nusantara, Sapto Trianggo Nurseto, Mochamad Husni Thamrin Muhammad Tajul Arifin, Mochamad Husni Thamrin PT. Pertamina Geothermal Energy, Skyline Building 19th Floor, Jl. M. H. Thamrin No.9, DKI PT. Pertamina Geothermal Energy (PGE), Jakarta, Indonesia, 10340 Indonesia

[email protected] [email protected]

Keywords: Hululais Volcanic Complex (HVC), Keywords: Hululais, Sumatra, geothermal, Suban Agung Fault (SAF), Hululais Geothermal volcanostratigraphy, volcanic facies Field (HGF). Hululais geothermal field is one of the The Hululais geothermal field in Bengkulu, exploration geothermal fields operated by PT Indonesia is one of the geothermal fields Pertamina Geothermal Energy (PGE). It is located developed by Pertamina Geothermal Energy in Rejang Lebong district, Bengkulu province, (PGE), situated on the western side of an Sumatra Island, Indonesia. Regionally, this field overlapping Ketahun and Musi Segment, which situated within Bukit Barisan Mountain range on is part of Great Sumatera Fault. Morphologically, the western side of an overlapping of two major the Hululais field stand within in Hululais fault segments. They are called Ketahun and Musi Volcanic Complex (HVC) consisting entirely of Segment. These are two segments of the Great Quaternary volcanic rocks. The orientation of Sumatran Fault complex. structural geology is predominantly northwest- In 2018, geological mapping was carried out to southeast (NW-SE). These structural trends are update the data of Hululais volcanostratigraphy consistent among surface and subsurface data, by PT PGE. 24 wells were successfully drilled to fault network, determined from map lineament complete the exploration and development interpretation, geologic mapping, gravity drilling stage on this field. Based on data data and borehole data. The most significant from surface geological mapping, subsurface structural features are the Suban Agung Fault (borehole data such as cuttings, cores and (SAF), this master fault strikes northwest through borehole image), remote sensing, and some HVC. The northwest trending SAF plays an updated modification reports from the important role in this system, affect a zone of previous researchers, Hululais field is part of the extension recent volcanism and controls the fluid quaternary Hululais Volcanic Complex (HVC) from circulations of Hululais geothermal system. quaternary. Ascertain of the fault network in Hululais The field comprises six main units (Bukit Resam, Geothermal Field (HGF) will assist to define Suban Agung, Bukit Beriti, Bukit Gedang, Bukit the most productive parts of the zone. Similar Lumut and Bukit Pabuar) with associated fault studies can be applied in other geologic primary/secondary deposits. structures to define the most permeable areas in the field. Poster

Poster

78 | 42nd New Zealand Geothermal Workshop 128 | TE AHI TIPUA KI TĀHORAKURI the Trust’s land which will protect, preserve, and A130: ESTABLISHING AN ECONOMIC possibly restore their wāhi tapu and taonga. DEVELOPMENT PLAN FOR WHANAU Moreover, we expect that the model presents a & HAPŪ IN DEGRADED GEOTHERMAL suitable template for other iwi and geothermal ENVIRONMENTS fields.

Lara Taylor, Tess Kora, Warner Kinita, Session 2.2 Anya Seward, Paul White, Diane Bradshaw

Tāhorakuri A130, Ngāti Tahu

Geothermal systems hold strong economic, cultural and scientific significance in the Taupō Volcanic Zone. Since their arrival many iwi have used these systems for cooking, heating and health; thus linking these iwi with their geothermal taonga throughout time. One local iwi, Ngāti Tahu, have been occupying land within the Ohaki Geothermal Field and on the banks of the since before the seven-waka arrived from Hawaikii. Their land has experienced significant adverse effects since the commissioning of the in the 1980’s. Extraction of fluids at depth has seen the loss of water flow to geothermal surface features, and the land has suffered from a large amount of subsidence, which has resulted in the migration of the Waikato River and flooding of a large portion of the A130 land block.

Tāhorakuri A130 Ahu Whenua Trust want to reconnect their whanau and economy with their geothermal taonga, with a vision of an eco- papakainga to provide work and housing to their whanau which sustainably utilises the resources that their land provides. In collaboration with GNS Science, the Trust will develop a model for reviving their land which will consider and promote: mātauranga-a-hapū, particularly pertaining to pre-geothermal development in the early-to-mid nineteenth century; western science (geology, geophysics, geochemistry and groundwater); and hapū culture and economic aspirations.

This project develops a deeper understanding of the damage and surface, subsurface and deeper impacts on the land and taonga, and aims at creating an effective plan for developing

23-26 November 2020 | 79 129 | MICROBIALLY INDUCED DEGRADATION the extent of degradation over the tower’s OF FIBRE REINFORCED PLASTIC (FRP) IN structure. Subsequent work considered a few THE COOLING TOWER OF A GEOTHERMAL possible ways to control bacterial growth and POWER STATION prevent the acid from accumulating. However, no suitable method could be found, with the T. Clark1, K. Wade2, N. Gibson3 decision taken to replace the affected FRP with 1 Geothermal Technical Resources, Mercury NZ new, acid-resistant FRP material. Because this Limited, Rotorua. type of degradation had not been previously reported, selection of new material required the 2 Scion, 49 Sala St, Rotorua 3010, New Zealand development of an accelerated aging test. This 3 Nga Awa Purua Power Station, Mercury NZ Ltd, test was extensively applied to FRP samples, Taupo covering a range of material formulations, allowing selection of suitable product for use [email protected] in the tower’s repair. This paper concludes with Keywords: Cooling towers, FRP, sulfuric acid, some observations about FRP formulations most corrosion, microbial degradation, sulfur oxidizing suited to this type of cooling tower service. bacteria, geothermal Session 5.2 Evaporative cooling water systems in geothermal power plants can pose several challenges for geothermal operators. The challenges of corrosion, deposition and biological control can be magnified in systems utilising direct contact condensers, due to the presence of hydrogen sulfide in the cooling water. Hydrogen sulfide provides an energy source for the growth of sulfur-oxidising bacteria, with the production of sulfuric acid as the main end-product. The sulfur oxidising bacteria can readily colonise such cooling towers, forming a biofilm on the large surface area provided by the tower’s structure and fill material.

This paper describes a technical investigation, undertaken following discovery of wide-spread degradation of the Fibre Reinforced Plastic (FRP) structure of a geothermal cooling tower, after only 7 years’ of service. The degraded FRP was found only in the top section of the tower, above the Drift Eliminator level. The subsequent investigation identified the cause of degradation as microbially-induced corrosion of the FRP material, due to the presence of sulfuric acid at about 1% concentration (pH 1). Several studies were conducted to understand the nature of the FRP degradation, its effect on the strength of the structural elements, and

80 | 42nd New Zealand Geothermal Workshop 130 | HE PUNA I RAWAKE, HE PUNA 131 | CFD MODELLING OF CORROSION WHAKATŌTŌ TEST LOOPS FOR GEOTHERMAL FLUID APPLICATIONS Dr Charlotte Severne1, Gayle Leaf1, Wairākei Charitable Trust2 Keith Lichti1, Rosalind Julian1, Cole Davies1, Bruno Fletcher2, Kazumi Osato3, Masatake Sato3, 1 The Māori Trustee Te Tumu Paeroa Kaichiro Kasai3, Norio Yanagisawa4, Koji Sakura5 PO Box 5038 Wellington 6140, New Zealand 1 Quest Integrity NZL Limited, PO Box 38096, Lower Hutt, New Zealand 2 Wairākei Charitable Trust The Secretary – Wairākei Charitable Trust, c/o PO Box 19,Turangi 2 Gulfstream Aerospace, 500 Gulfstream Road, Savannah, GA 31408, USA [email protected] 3 Geothermal Energy Research & Development Keywords: Taupō, Ngātoroirangi, Tūwharetoa, Co., Ltd. (GERD), Shinkawa-1 Chome, Chuo-ku, Tia, hapū, iwi, manawhenua, exploration, Tokyo 104-0033, Japan tourism, energy. 4 Renewable Energy Research Center, AIST, 2-2-9, In December 1880, a claim seeking an Machiikedai, Koriyama, Fukushima 963-0298, investigation of the land described as lying Japan between Wairākei Stream in the North and Waikato River in the east, the Waipuwerawera 5 TenarisNKKTubes, 1-10, Minamiwatarida, Stream in the south and the boundary of the Kawasaki, Kanagawa, 210-0855, Japan Oruanui Block in the west, was confirmed [email protected] as the Wairākei Block. This land has passed through three significant occupation stages. Keywords: geothermal, corrosion, scaling, The Manawhenua Landscape was the early monitoring, test loop, CFD, field testing settlement of the Taupō environs by Māori Small bore corrosion test loops in side streams voyagers and explorers. Descendants of those have been commonly used for many years early arrivals are reflected in the whakapapa of in the oil and gas industry for cooling water the hapū who thrived in the area. They were the corrosion monitoring. This work describes a kaitiaki, living alongside and utilising the natural high temperature flowing brine test loop for resources abundant across their whenua. In on-line Electrical Resistance, Linear Polarisation the 1870’s the Tourism Landscape was imposed; Resistance and ASTM coupon exposure testing Victorian tourists arrived to experience the in geothermal applications. CFD modelling of natural wonders of geysers, hot pools and the Electrical Resistance probe access points fumaroles. Kaitiaki no longer had unfettered is presented for small bore piping in “T” and access to the whenua and its taonga. The third “Y” configurations that achieve mass flow rates stage, the Energy Landscape, was ushered in similar to pipeline conditions while minimizing with the construction of the geothermal power the effects of the test element finger intrusion project. Understanding how these stages have into the flowing brine stream. impacted on the whenua and its kaitiaki is important for the restoration and rehabilitation Session 5.2 of their mana i te whenua.

Session 2.2

23-26 November 2020 | 81 134 | SURFACE HEAT LOSS ASSESSMENT OF Calculated evaporative surface heat loss from the ROTORUA GEOTHERMAL FIELD surveyed geothermal pools is estimated to be 248 MW. Total heat loss (evaporative, discharging Anya Seward1, Rob Reeves1, Penny Doorman2, flow, convective and conductive heat losses) for Fiona Sanders1, Sabine Lor3, Nick Macdonald1, the areas surveyed is estimated to be 299 MW. Thomas Brakenrig1 and Duncan Graham1 This encompasses approximately 80% of the 1 GNS Science, Wairakei Research Centre, Private thermal areas in the RGF. Bag 2000, Taupo 3352, New Zealand Session 4.2 2 Bay of Plenty Regional Council, P.O. Box 364, Whakatane 3158, New Zealand 136 | TURBULENCE MEDIATED RAPID ALUMUINOSILICATE FORMATION 3 Grenoble Institute of Technology, ENSE3, 46 IN HYDROTHERMAL VEIN BRECCIA: avenue Felix Viallet, F38031 Grenoble, France NGATAMARIKI GEOTHERMAL [email protected] POWERSTATION, NEW ZEALAND

Keywords: Rotorua, Geothermal Surface Claire J Newton features, heat loss, heat flux Mercury, Ngahere House 283 Vaughan Road, Rotorua City is built around the active Rotorua Owhata, Rotorua, New Zealand Geothermal Field (RGF) which is valued for its [email protected] areas of surface activity utilised for cooking, bathing, heating, and tourism. Understanding Keywords: Aluminosilicate, aluminous, silica and monitoring changes in this dynamic boehmite, aluminium, scale, precipitation, binary, geothermal system is crucial in allowing the hydrothermal. resource to be used sustainably, while protecting A recent cleanout of a geothermal brine- the natural geothermal surface features. Changes pentane heat exchanger at the Ngatamariki in activity of geothermal features over time can geothermal power station provides valuable indicate changes that may be occurring within insight into the in-situ formation processes of the geothermal reservoir due to either natural both hydrothermal vein breccias and geothermal or anthropogenic causes. Estimating heat loss aluminosilicate scales. Samples of the scale from a geothermal field provides an indication breccia taken during the cleanout primarily of thermal activity present in the geothermal consist of broken fragments of a dark-coloured system at depth. We present a surface heat amorphous aluminosilicate pipe scale, which loss assessment of the Rotorua geothermal was remobilised and redeposited within the system and compare the results to earlier heat heat exchanger over a period of ~12-hours loss surveys, to assess changes in surface heat during the early stages of the breccia forming output. Flow rates, water temperatures and event. This dark coloured clastic component was chemistries of major flowing springs and streams subsequently cemented with a white-coloured, were measured, as well as water temperatures massive to very fine-grained amorphous and surface areas of large geothermal pools. aluminosilicate matrix over the course of weeks. Calorimetry and ground temperature profiles Scanning Electron Microscope (SEM) analyses were also collected from areas of ambient, indicate that the dark component of the breccia heated and steaming ground. Evaporative formed relatively slowly via colloid impact as a heat loss is a key component of the total heat pipe-wall scale before separating from the pipe loss when there is a large surface area of water wall prior to its remobilisation. In contrast, the associated with naturally occurring geothermally white fraction of the breccia appears to have heated springs and pools (as occurs in Rotorua).

82 | 42nd New Zealand Geothermal Workshop precipitated quasi-instantaneously in place, likely 137 | A ROBUST SUPERCRITICAL as a result of the turbulence induced flashing GEOTHERMAL SIMULATOR caused by the earlier deposited clastic scale John O’Sullivan1, Juliet Newson2, Sam Alcaraz3, obstructing flow into the heat exchanger tubes. Sam Barton2, Richmond Baraza4, The rapidly formed white aluminosilicate fraction Adrian Croucher1, Samuel Scott2 and served to seal voids within the breccia, forming Mike O’Sullivan1 a strong cementing matrix. The volume and rate of white amorphous aluminosilicate precipitation 1 Department of Engineering Science and was significant, with the breccia consisting of Geothermal Institute, University of Auckland, up to ~20vol.% white aluminosilicate matrix. A New Zealand fine white aluminosilicate powder discovered 2 Iceland School of Energy, Reykjavik University, immediately downstream of the breccia appears Iceland identical to the white aluminosilicate breccia cement, although unlike the aluminosilicate 3 GNS Science, Wairakei Research Centre, Private cement it contains ≥4 w.t.% of the aluminium Bag 2000, Taupo 3352, New Zealand oxyhydroxide mineral, boehmite. Knowledge 4 Geothermal Development Company, Kenya gained from the investigation of this event yields invaluable information, both for the prevention [email protected] of similar scaling events in the future, and the Keywords: Geothermal modelling, supercritical, understanding the formation mechanisms of Menengai, Reykjanes, Krafla, Taupo volcanic zone geothermal aluminosilicate scales generally. Furthermore, this event provides unique insight Recent improvements to a supercritical into the interaction between some physical and equation-of-state (EOS) for the simulator chemical processes which also occur within TOUGH2 are discussed together with its active natural hydrothermal systems. application to simulations of Menengai (Kenya), Reykjanes Peninsula (Iceland), Krafla (Iceland) and Session 6.3 the TVZ (New Zealand). The models of Reykjanes Peninsula and the TVZ include multiple geothermal systems.

The new EOS uses smoother and more reliable transitions into and out of the supercritical region than our previous supercritical EOS. This allows natural state simulations to converge robustly, thus enabling models to be calibrated effectively.

An air/water equation-of-state, similar to EOS3 in TOUGH2, but with supercritical capability is also described. This new EOS3sc allows simulation of regions including the shallow unsaturated zone and extending deep to the high-temperature and high-pressure zone.

Session 6.2

23-26 November 2020 | 83 138 | GEOLOGICAL MODEL AND 139 | A CONCEPTUAL APPROACH TO PERMEABILITY FRAMEWORK OF BUKIT 3-D “PLAY FAIRWAY” ANALYSIS FOR DAUN GEOTHERMAL FIELD, INDONESIA GEOTHERMAL EXPLORATION AND DEVELOPMENT Muhammad Ikhwan1, Irene C Wallis2 and Julie V Rowland2 Bastien Poux1, Jeremy O’Brien2

1 Pertamina Geothermal Energy, Skyline Building 1 Seequent Canada limited, Suite 300, 860 Homer Level 19th, Jalan M. H. Thamrin No.9, Jakarta, Street, Vancouver, British Colombia V6B 2W5, Indonesia Canada

2 School of Environment, University of Auckland, 2 Seequent Limited, 20 Moorhouse Avenue, 23 Symond Street, Auckland, New Zealand Addington, Christchurch 8010, New Zealand

[email protected] [email protected]

Keywords: Bukit Daun, Sumatra, exploration, Keywords: Play Fairway, Resource exploration, geology and structural modelling, borehole 3-D modelling, Leapfrog image logs, permeability. “Play fairway” analysis has long been utilised in We present results from a study that investigates the hydrocarbon industry to assess exploration the geological setting of Bukit Daun geothermal risk from regional to prospect-level scales. More field, Indonesia and how that geology may recently this methodology has seen increased influence hydrology. Our analysis addresses traction in the geothermal industry and resulted geologic controls from the regional to the in a series of studies in the US. Some of the wellbore scale, and incorporates data provided projects include the states of Hawai’i (Lautze by Pertamina Geothermal Energy with publicly et al., 2015, 2016, 2019), Nevada (Faulds et al., available terrain images and geologic data. 2018, 2016, McConnville et al, 2017) and Utah Extensive use of the regional geologic setting (Wannamaker et al, 2016, 2017). (i.e., outside the prospect area) enabled us to In a play fairway analysis, several parameters improve the confidence and plausibility of the potentially indicating the presence of a geologic interpretation. geothermal resource at depth are categorized, We developed a 3D geologic and structural weighted and combined together. This provides model and used it as a framework for a spatial distribution of the geothermal resource hydrologic interpretation that is based on favourability to limit exploration risk. These well temperature profiles, feedzone locations, analyses are generally limited to the compilation distribution of surface manifestations, and shape of surface data or results from past surface- of the clay cap. Pertamina Geothermal Energy’s based surveys for extended geographical drilling success discovered a potentially viable areas, although some parameters such as the resource and our study proposes a hydrologic geothermal gradient are calculated using model for that resource. Our analysis identifies dispersed well data. those elements of the geology that may In this paper, a 3-D conceptual approach to the influence fluid flow at the reservoir and wellbore play fairway methodology is introduced, based scale. on the existence of sub-surface data obtained at Session 1.3 the project scale from advanced geological and geophysical surveys, drilling of exploration and/ or development wells, laboratory analyses and well testing. A 3-D subsurface modelling tool

84 | 42nd New Zealand Geothermal Workshop was used to integrate the various types of data it runs for another 40 years, a total production life and then perform calculations and conditional of 100 years since commissioning. queries using a gridded block model, resulting Two different resource assessment methods in a favourability Index model of the geothermal were investigated: the volumetric (stored heat) resource method, and also Experimental Design (ED) Additionally, this 3-D favourability Index model and Response Surface Methodology (RSM). is always based on the best understanding of In particular, the use of the Plackett-Burman the resource as it will dynamically update when design for building a polynomial model using new data is integrated. The model can also be a calibrated natural state reservoir model with refined with additional parameters relevant to minimum number of required simulation runs specific projects (e.g. local legislative constraints). was investigated. The methodology and the calculations created Results obtained from Plackett-Burman suggest can easily be transferred to any other geothermal that Wairakei could sustain a P50 of 294 MWe field dataset to compare results providing a for 50 years and 219 MWe for 100 years since repeatable workflow allowing prospects to be commissioning. Findings also reveal that easily benchmarked or compared. permeability and injection parameters are critical Session 2.3 to sustain operation for the first 50 years while sufficient permeability and porosity are crucial to 140 | ESTIMATING WAIRAKEI’S 50 YEARS support the operation up to 100 years. AND 100 YEARS MWE POTENTIAL CAPACITY Session 1.2 FROM A CALIBRATED NATURAL STATE MODEL USING EXPERIMENTAL DESIGN (ED) AND RESPONSE SURFACE METHODOLOGY (RSM)

Anthony E. Ciriaco1, Sadiq J. Zarrouk1 and Katie McLean2

1 Department of Engineering Science, The University of Auckland, Private Bag 92019, Auckland, New Zealand

2 Contact Energy Ltd., Wairakei Power Station, Taupo, New Zealand

*[email protected]

Keywords: Wairakei, probabilistic resource assessment, natural state model, polynomial model, Plackett-Burman.

Wairakei geothermal field has been operating since 1958, which is years beyond the initial expected production life. There is still significant hot geothermal fluid available for electricity generation that can sustain production for many more years. It is interesting to estimate the theoretical capacity (MWe) of the field assuming

23-26 November 2020 | 85 141 | BUOYANCY VORTEX POWER FROM 142 | CONCEPTUAL MODEL EVOLUTION OF LOW-TEMPERATURE HEAT: PROGRESS THE TAUHARA GEOTHERMAL RESERVOIR FROM 1960-2020 N.A. Hawkes1, R.G.J. Flay1, J.E. Cater2, M. MacDonald1 Julian McDowell, Paul Bixley and Fabian Sepulveda 1 Department of Mechanical Engineering, University of Auckland, New Zealand Contact Energy, Private Bag 2001, Taupo 3352, New Zealand 2 Department of Engineering Science, University of Auckland, New Zealand [email protected]

[email protected] Keywords: Tauhara, conceptual model, reinjection, pressure response, deep permeability, This paper is a progress report since NZGW compartmentalization. 2018, describing laboratory results and a scaling or non-dimensionalisation of atmospheric At the early stages of reservoir exploration buoyancy vortices for power generation. It is the conceptual model for the geothermal based on the Oberbeck-Boussinesq assumption resource is of necessity simple. As a reservoir and assumes that the vortex flows are pseudo- is developed the conceptual model will be cyclostrophic and that a radial Richardson refined as new spatial and temporal information number can serve as a predictor of the onset becomes available from additional drilling and of Kelvin-Helmholtz instability leading to a extended monitoring of the reservoir response transition to a turbulent plume. This is used to production and reinjection. Pressure response to locate the cold reservoir of the vortex of the early exploration wells at the Tauhara when viewed as a heat engine. It permits the reservoir, drilled in the 1960s some 5-10 km prediction of the behaviour of large vortices in distance from production areas at Wairakei (first the atmosphere by using data from experiments power generation 1958), indicated the existence on small vortices. of a relatively shallow and laterally extensive hydraulic connection between the Tauhara Session 6.2 and Wairakei reservoirs. The pressure difference between the reservoirs implied that part of the Wairakei hot recharge was derived from Tauhara. Over time, the conceptual model has evolved, incorporating data from new, deeper wells, together with geophysical surveys, and the reservoir response to changing volumes of production and reinjection fluids. The evolution of the conceptual model for the Tauhara reservoir over the last 60 years is presented along with the current understanding of the nature of the interconnections between Wairakei and Tauhara.

Session 1.3

86 | 42nd New Zealand Geothermal Workshop 23-26 November 2020 | 87 Notes

88 | 42nd New Zealand Geothermal Workshop Notes

23-26 November 2020 | 89 www.geothermalworkshop.co.nz