Geothermal Engineering: Fundamentals & Synergies With
Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering
Prof. Dr. Gioia Falcone Institute of Petroleum Engineering Dept. of Geothermal Engineering & Integrated Energy Systems
Geneva, 25th April 2013
Outline • Geothermal within the energy arena • Fundamentals of geothermal energy • Types of geothermal resources • Uses of geothermal energy • Oil & gas expertise for geothermal exploitation • Conclusions
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 2 Fuel Shares of World Total Primary Energy Supply (2010)
(IEA 2012)
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 3 World Electricity Generation (TWh) from Non-Hydropower Renewables by 2030
Concentrating Solar Power
Photovoltaic
(ESMAP, 2012)
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 4 Cost-Competitiveness of Renewables
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 5 Constant Base Load Production from Geothermal vs. Other Energy Sources
(ESMAP, 2012)
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 6 2010 World* CO2 Emissions** by Fuel
(IEA, 2012)
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 7 US CO2 Emissions by Primary Energy Source
(ESMAP, 2012)
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 8 Outline • Geothermal within the energy arena • Fundamentals of geothermal energy • Types of geothermal resources • Uses of geothermal energy • Oil & gas expertise for geothermal exploitation • Conclusions
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 9 The Earth’s Heat -1
(Gupta & Roy, 2007 )
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 10 The Earth’s Heat -2
Total heat flow observed on the Earth’s surface (& T distribution within it) is due to:
● Release of heat due to the cooling of the Earth
● Heat produced by radioactivity (amount of radioactive elements present in rocks releases enough heat to account for ~60% of total heat flow for continental crust)
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 11 The Earth’s Heat -3 ● Earth’s cooling process is very slow ● Temperature of mantle has decreased by 300-350°C in 3 billion years, remaining at ~4000°C at its base ● 99% of Earth is hotter than 10000C ● 99% of the 1% is hotter than 1000C
(Geothermal Education Office) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 12 Proof of temperature at depth… Direct measurements of T in the Earth’s interior currently limited to a depth of 12.261 km in the Kola super-deep borehole SG-3 (northwest of Russia), with BHT of 180oC.
Another reliable measurement of T at great depth is in the 9.101-km deep KTB borehole in Oberpfalz, Germany, with BHT of 265oC.
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 13 Plate Boundaries & Geothermal Spots
(Geothermal Education Office )
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 14 Plate Tectonics
(Geothermal Education Office )
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 15 Geothermal Systems
Convection & conduction
(Dickson & Fanelli, 2004 ) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 16 Essential Requirements for a Geothermal System to Exist
(1) a large source of heat (2) a reservoir to accumulate heat (3) a barrier to hold the accumulated heat
Analogy with petroleum systems
(after Gupta & Roy, 2007 )
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 17 Outline • Geothermal within the energy arena • Fundamentals of geothermal energy • Types of geothermal resources • Uses of geothermal energy • Oil & gas expertise for geothermal exploitation • Conclusions
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 18 Types of Geothermal Systems
. Vapour-dominated . Hot water . Geo-pressured . Magma . Hot Dry rock (HDR) & Enhanced Geothermal Systems (EGS)
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 19 Vapour-Dominated
Most exploited fields contain water at high P & T>100 oC.
When this water is brought to surface, P is reduced and a mixture of saturated steam & water is generated.
There are only few geothermal fields producing superheated steam with no associated fluids (dry steam fields).
(Gupta & Roy, 2007 )
Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 20 Hot Water
Differ from vapour-dominated fields in that they are characterised by liquid water being the continuous fluid phase.
Typically, 60 oC (Gupta & Roy, 2007 ) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 21 Geo-pressured Typically form in a basin in which very rapid filling with sediments takes place, resulting in higher than normal pressure of the hydrothermal water. Often saturated with methane. First identified in the deep sedimentary layers underneath the Gulf of Mexico. Wells flow pressurised to the surface. Water T is 90-200°C. (Gupta & Roy, 2007 ; Texas Renewable Energy Resource Assessment, 2009) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 22 Magma Magma is the ultimate source of all high-temperature geothermal resources. Typically, magma crystallizes to form igneous rocks at temperatures varying from 600 to 1400 oC. Magma has been encountered in situ 3 times during drilling projects—twice in Iceland, and once in Hawaii. However, up to now, the necessary technology has not been developed to recover heat energy from magma. (Gupta & Roy, 2007 ) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 23 Hot Dry Rock (HDR) Hydrothermal resources restricted to countries with favourable geological conditions (i.e. plate boundaries). HDR resources exist where the heat is stored in hot & poorly permeable rocks at shallow depths within the Earth’s crust, without fluid availability to store or transport the heat. HDR is the new frontier of geothermal energy and possibly the area closest to petroleum exploitation Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 24 HDR Concept C 0 Depth, m Depth, Temperature, Temperature, (MIT, 2006) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 25 From HDR to „Deep Geothermal“ • Hot Dry Rock concept first implemented at Fenton Hill in 1977 • Heat stored in deep seated, conductive/radiogenic dominated, tight sediments & hard crystalline basement rocks. • Volcanic, metamorphic, magmatic or sedimentary settings. • Dry / not dry • W-w/o pre-existing fractures or fissures • Also known as: . Hot Fractured Rock . Hot Wet Rock . Enhanced (or Engineered) Geothermal System (EGS) . Deep Heat Mining . Deep Earth Geothermal Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 26 Why Deep? (Breede et al., 2012) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 27 Outline • Geothermal within the energy arena • Fundamentals of geothermal energy • Types of geothermal resources • Uses of geothermal energy • Oil & gas expertise for geothermal exploitation • Conclusions Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 28 Geothermal Energy Uses 1. Direct Use & District Heating Systems 2. Geothermal Heat Pumps 3. Electricity Generation Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 29 Geothermal Energy Use vs. Field T (*) The above are indicative T value only! As technology advances, the T cut-off point changes. (after ESMAP, 2012) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 30 Direct Use & District Heating Geothermal Education Office Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 31 Geothermal Heat Pumps (DOE) Heating Cooling Geothermal heat pumps use the stable temperatures of the ground (vertical well typically 100-400 ft deep) as a heat source to warm buildings in winter and as a heat sink to cool them in summer. Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 32 Deep Borehole Heat Exchanger (Rybach, 1994) (Kohl et al., 2000) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 33 Geothermal Power Plants (Geothermal Education Office) Lardarello (Italy): 1st plant in the world Still running after 100 yrs! Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 34 Geothermal-Electric Installed Capacity by Country in 2009 (IPCC, 2011) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 35 Geothermal Power: Installed Capacity Worldwide in 2010 (ESMAP, 2012) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 36 Outline • Geothermal within the energy arena • Fundamentals of geothermal energy • Types of geothermal resources • Uses of geothermal energy • Oil & gas expertise for geothermal exploitation • Conclusions Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 37 Oil & Gas Expertise for Geothermal Exploitation Drilling, Completions, Fracturing & Geology & Geophysics Production Ops. Flow in Porous Media (Enel, 2005) Field Performance Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 38 Geo-modelling & Reservoir Simulation Geology & Geophysics • Fracture imaging and characterization Flow in Porous Media Basic mass conservation equations governing the flow of multiphase, multicomponent fluids in permeable media Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 39 Geothermal Reservoir Modelling - Issues • Non-isothermal flow • Phase change (boiling & condensation) • Highly non-linear nature of water-steam flow. • Geologies typically include CO2 & NaCl. • Fracture-dominated reservoirs cannot be adequately described with single-porosity. • Significant heat transfer effects on multiphase flow encountered in geothermal applications. Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 40 Drilling, Completions, Fracturing & ProductionFracturing Ops. Multiphase Flow in Wells & Production Lines Drilling & Completions Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 41 Drilling & Completions -1 (DOE, 2006) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 42 Drilling & Completions -1 Success rate for geothermal wildcat wells is only 25 - 40 % a reduction in exploratory drilling costs would be a major incentive for increased geothermal exploitation. Drilling costs are only a part of the total well expenditure. Tubulars can double total well cost. Drilling & completions can account for > 1/2 of the capital cost of a geothermal power project. (DOE, 2006) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 43 Drilling & Completions -2 • Geothermal wells need submersible pumps to lift the heated fluids to surface. • Large-diameter production casing needed in HDR wells (amount of fluids to be pumped & associated high enthalpy). • Pumps must be deployed in a straight hole & installed at a certain depth to ensure a sufficient water head. (SPE 113852) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 44 Drilling & Completions -3 • Drilling fluids are subject to thermal degradation of chemical additives, which causes highly variable rheological & filtration properties. Reduced molecular interaction & viscosity in mud. • Even without degradation, viscosity of hydrosoluble polymer solutions, used in muds, strongly decreases as temperature > 65°C. • Current experience with HPHT drilling for oil & gas can be readily transferred to the geothermal sector. • Testing labs already have mud viscometers working up to 275 MPa & 315°C. (SPE 113852) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 45 Drilling & Completions -4 • Setting depth of production casing must ensure downhole pump is submerged at max flow rate. • New geothermal projects need casing diameters larger than 9 5/8”. • Thermally-induced casing fatigue & cement integrity are key issues for HDR wells as expected life time is longer than for oil & gas wells. • Premium casing connections offer excellent resistance to axial loads vs. leak resistance, but their high cost impairs the economics of marginal geothermal projects. Typical completion for (SPE 113852) a HDR producing well Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 46 Flow in Wells: Oil & Gas vs. Geothermal Commonly, flow in geothermal wells is water-steam. 2-phase well flow models already widely used in oil & gas industry. (SPE 113852) 2-phase flow map (Duns & Ros, 1963). Blue points are data from geothermal wells (Garg et al., 2005) Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 47 Flow in Geothermal Wells: Issues • Wellbore simulators for fluid & heat flow already developed, yet limited ability to match field data. • Geothermal wellbore simulator must handle 2-phase, 3-component mixtures (H2O-NaCl-CO2). • With relevant salt content in the produced fluids, these become superheated steam ∆P along the well larger than for pure H2O, due to higher fluid ρ & μ and lower specific enthalpy. • 2-phase P gradients of H2O-CO2 and H2O-CO2-NaCl mixtures smaller than in 2-phase pure H2O flows. Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 48 Fracturing Geothermal Wells • Fracturing is key in HDR / EGS projects, where good hydraulic conductivity must be created between injection & production wells. • Oil & gas fracturing techniques in HDR geothermal settings have not been fully successful. Open fractures have short-circuited or not connected to existing natural fractures. Also, induced seismicity… • Need for new developments to incorporate dynamic poroelastic & thermoelastic effects in the formations penetrated by the fractures. Chemical stimulation also applied to geothermal wells Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 49 Conclusions • Geothermal energy, especially HDR/EGS, is a renewable resource that can help meet the world’s growing demand. • Oil & gas expertise fully complements geothermal exploitation. Many areas exist where technology transfer between these energy sectors should be enhanced. Prof. Dr. G. Falcone Institute of Petroleum Engineering Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering 50 Geothermal Engineering: Fundamentals & Synergies with Petroleum Engineering Prof. Dr. Gioia Falcone Institute of Petroleum Engineering Dept. of Geothermal Engineering & Integrated Energy Systems Geneva, 25th April 2013