SUMMARY TECHNICAL REPORT of CO2SINK
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CO2SINK Summary Technical Report SUMMARY TECHNICAL REPORT of CO2SINK SES6-CT-2004-502599 CO2SINK In-situ R&D Laboratory for Geological Storage of CO2 Integrated Project Thematic Priority: 6.1.ii Start date of project: 01.04.04 Duration: 72 months Project co-funded by the European Commission within the Sixth Framework Programme (2002-2006) Dissemination Level PU Public PP Restricted to other programme participants (including the Commission Services) RE Restricted to a group specified by the consortium (including the Commission Services) CO Confidential, only for members of the consortium (including the Commission Services) 1 CO2SINK Summary Technical Report CONTENT SUMMARY .................................................................................................................. 3 INTRODUCTION ....................................................................................................... 88 GEOLOGICAL AND HYDROGEOLOGICAL SITE CHARACTERIZATION ......... 1212 LABEXPERIMENTS: ROCK FLUID INTERACTION ............................................ 1818 DYNAMIC FLOW MODELING .............................................................................. 2222 RISK ASSESSMENT ............................................................................................ 2727 SITE PREPARATION AND INJECTION FACILITY .............................................. 3131 EXPERIENCES OF STORAGE OPERATION ...................................................... 3838 MONITORING CO2 MIGRATION .......................................................................... 4141 DISSEMINATION AND PUBLIC OUTREACH ...................................................... 5454 OUTLOOK ............................................................................................................. 5959 2 CO2SINK Summary Technical Report Chapter 1 SUMMARY Hilke Würdemann1, Günter Borm 1,2,Frank R. Schilling1,2 1Helmholtz Centre Potsdam, German Research Centre for Geosciences (GFZ), Telegrafenberg, 14473 Potsdam, Germany 2 Universität Karlsruhe, KIT, Engler-Bunte-Ring 14, 76131 Karlsruhe, Germany 3 CO2SINK Summary Technical Report The CO2SINK (CO2 Storage by Injection into a Natural Saline Aquifer at Ketzin) pilot project aimed for a better understanding of geological CO2 storage in a saline aquifer. The main focus of the project was the development and testing of monitoring techniques. Furthermore, CO2SINK served as a test site for CO2 injection and safety measures. Through the European project CO2SINK the most advanced monitoring project of the subsurface worldwide was established. It triggered a broad variety of national and international activities, which contributed greatly to the success of the storage operation. The EUROGIA Projects COSMOS (GEOTECHNOLOGIEN Germany), COSMOS I (France) and COSMOS II (France) on monitoring strategies, the EU FP6 projects GRASP and CO2ReMoVe allowed for a European wide capacity building. The German Projects CORTIS provided the CO2 supply whereas the project CORDRILL enabled the project to drill three wells; both were funded by industrial partners and the German Ministry of Economy and Technology (BMWi – COORETEC Initiative). The Project CHEMKIN (development of new sensors – financed by GEOTECHNOLOGIEN programme of the German Ministry of Education and Research (BMBF) supported the development of a new gas membrane sensor. CO2SINK triggered national and international activities, allowed for a better connection and interaction of European Scientists and Companies and supported the European legislation process. A broad outreach project was a necessity to gain public acceptance for the project and is used as a lighthouse project in Europe, for Science, R&D activities, public acceptance and networking. Food-grade CO2 was injected into Upper Triassic sandstones (Stuttgart Formation) of a double-anticline structure. The Stuttgart Formation represents a fluvial environment composed of sandstone channels and silty to muddy deposits. Undisturbed, initial reservoir conditions are ~ 35 °C and 62 bar at depth of injection at 650 m below surface. The initial reservoir fluid was highly saline with about 235 g/l total dissolved solids primarily composed of sodium chloride with notable amounts of calcium chloride. The initial pH value was 6.6. Hydraulic tests revealed a permeability between 50 and 100 mDarcy for the sand channels of the storage formation. The anticline forms a classical multibarrier system: The first caprock is a playa type mudstone of the Weser and Arnstadt formations directly overlying the Stuttgart formation. Laboratory tests revealed permeabilities in a µDarcy-range. The second main caprock is a tertiary clay, the so-called Rupelton. Maximum injection pressure reservoir integrity tests resulted in values of about 120 bar for the first cap rock. Due to safety standards, the pressure threshold was set to 82 bar until more experience on the reservoir behaviour was available. The sealing property of the secondary cap rock was well known from natural gas storage operations at the testing site and was the basis for the permission by the mining authority to operate the CO2 storage. th CO2 injection started on 30 June 2008 and by end March 2010 - after 21 months a total of 33,000 tons of CO2 has been injected. This is slightly more than half of the original target of up to 60,000 tons. The injection was operated successfully and safely. The mean injection rates were around 67 tons of CO2 per day when in service. The monitored wellhead pressure was almost constant at 63 to 64 bar and the calculated flow pressure at reservoir depth was 77 to 78 bar. 4 CO2SINK Summary Technical Report The effects of CO2 injection were observed with surface and downhole measurements. A long-term field monitoring of natural diffusive CO2 soil gas emissions, gas fluxes along faults and fissures as well as CO2 dissolved in regional ground waters at shallow levels with different commercially available geochemical sensors has been conducted over the whole life time of the project. To date no evidence of any gas seepage or leakage from the CO2 storage reservoir has been detected. Spreading of the CO2 plume in the reservoir was monitored by a broad range of geophysical and geochemical techniques. Three wells (one injection and two observation wells) were equipped with “smart casings” containing electrodes for Electrical Resistivity Tomography (ERT) behind casing, facing the rocks and a Distributed Temperature Sensing (DTS). Changes in borehole temperatures were continuously monitored since the start of CO2 injection with permanently installed downhole fiber-optic sensor cables using DTS. In-situ saturation changes were monitored by repeated pulsed neutron-gamma wire line logging, as well as a heat pulse technique using an electrical heater cable installed parallel to the DTS sensor cables. A newly developed Gas Membrane Sensor (GMS), enabling a continuous monitoring of the gas composition in the observation wells (OWs), observed the arrival of CO2 and gaseous tracers at the observation wells. CO2 arrival was detected at the first OW (50 m away from injection) after about 500 tons of injected CO2 on July 15, 2008. Arrival at the second OW (at 112 m distance) was recorded after about 11,000 tons of injected CO2 on March 21, 2009. Pressure and temperature logs revealed a supercritical state of the CO2 in all three wells at depth of the storage formation after arrival of CO2. The propagation of the carbon dioxide plume in the underground was observed with seismic and geoelectrical measurements as well. Repeated seismic measurements indicated changes in the elastic properties of rocks due to the influence of carbon dioxide. Repeated geoelectrical observations imaged changes in the electrical conductivity caused by the injection of carbon dioxide. Both methods allowed the performance of long-term observations of the carbon dioxide during injection phase. The seismic monitoring included crosshole seismic experiments, Vertical Seismic Profiling (VSP) and Moving Source Profiling (MSP), star seismic experiments and 4-D seismics. Seismic measurements for structural interpretation and baseline characterization were carried out in 2005 and 2007 using different methods in order to cover the near-injection to the regional scale. Time-lapse crosshole seismics showed no considerable changes in seismic velocity between the two observation wells within the first two repeats after injection of 660 tons and 1,700 tons of CO2, respectively. However, after injection of 18,000 tons CO2 all time-lapse surveys showed a clearly observable signature of the CO2 propagating in the Stuttgart formation. In summer and fall 2009 surface-downhole observations (MSP, 2D and 3D surface surveys) were repeated providing a multi-scale view on the time-lapse effect of more than 20,000 tons of injected CO2. The crosshole tomography revealed a significant reduction of propagation velocity within the injection horizon, while MSP and surface reflection surveys revealed both an increased reflectivity from the depth range of the top of the 5 CO2SINK Summary Technical Report Stuttgart Formation around the injection location which can be attributed to a signature of the CO2 migration in the reservoir. Electrical Resistivity Tomography (ERT) proved to be sensitive to saturation changes caused by propagation of supercritical CO2 within the reservoir. Forward modeling indicated an increase of electrical resistivity of about 200 % caused by CO2 injection, which is verifiable in the field data from geoelectrical