GEOTHERMAL RESERVOIR ENGINEERING Prof. Dr. Mahmut PARLAKTUNA MIDDLE EAST TECHNICAL UNIVERSITY PETROLEUM AND NATURAL GAS ENGINEERING INTERNATIONAL SUMMER SCHOOL ON GEOTHERMAL GEOCHEMISRTY 02-15 June 2003 İzmir - TURKEY

Prof. Dr. Mahmut PARLAKTUNA 11-22 Haziran 2002 RESERVOIR ENGINEERING Determination of well locations Planning and interpretation of well measurements (well logging, production rates, etc.) Determination of production mechanism Performance prediction studies of reservoir behavior International Summer School on Geothermal Geochemistry June 11, 2003 International Summer School on Geothermal Geochemistry

Prof. Dr. Mahmut PARLAKTUNA 11-22 Haziran 2002 RESERVOIR ENGINEERING ULTIMATE GOAL Determination of optimum production conditions to maximize the heat recovery from the reservoir under suitable economic conditions International Summer School on Geothermal Geochemistry June 11, 2003 International Summer School on Geothermal Geochemistry

QUESTIONS TO BE ANSWERED Most suitable development plan of the reservoir Number of wells with well pattern Production rates of the wellbores Heat that will be recovered Change in reservoir temperature with time Enhanced recovery techniques to increase the heat recovery from the reservoir International Summer School on Geothermal Geochemistry June 11, 2003

International Summer School on Geothermal Geochemistry STEPS Define the physical processes and develop the conceptual model of the reservoir Determine the physical and chemical properties of reservoir rock and fluid Develop the mathematical and physical models of the reservoir with the help of existing data. Define initial and boundary conditions International Summer School on Geothermal Geochemistry June 11, 2003

SOME FACTORS SPECIFIC TO GEOTHERMAL RESERVOIRS Relatively high reservoir temperatures Volcanic origin of rocks with highly fractured characteristics Chemical precipitation of solids within the reservoir during production Boiling of water within the reservoir and/or wellbore International Summer School on Geothermal Geochemistry June 11, 2003

International Summer School on Geothermal Geochemistry GEOTHERMAL SYSTEMS Required conditions A heat source A heat carrier (except HDR) Reservoir rock Caprock International Summer School on Geothermal Geochemistry June 11, 2003

International Summer School on Geothermal Geochemistry GEOTHERMAL SYSTEMS (Dickson and Fanelli, 1995) International Summer School on Geothermal Geochemistry June 11, 2003

International Summer School on Geothermal Geochemistry GEOTHERMAL SYSTEMS Vapor dominated systems Liquid dominated systems Geo-pressured reservoirs Hot dry rock (HDR) International Summer School on Geothermal Geochemistry June 11, 2003

ENERGY DENSITIES OF GEOTHERMAL SYSTEMS International Summer School on Geothermal Geochemistry June 11, 2003

Prof. Dr. Mahmut PARLAKTUNA 11-22 Haziran 2002 ASSUMPTIONS A hypothetical geothermal reservoir Porosity = 20 % Initial pressure = 47 bar Initial temperature = 260  C 7 bar pressure decline due to fluid production The reservoir fluid is at either saturated liquid or saturated vapor state International Summer School on Geothermal Geochemistry June 11, 2003 International Summer School on Geothermal Geochemistry

Prof. Dr. Mahmut PARLAKTUNA 11-22 Haziran 2002 SCENARIOS Scenario-1 Originally water, remaining water Scenario -2 Originally water, becoming steam Scenario -3 Originally steam, remaining steam International Summer School on Geothermal Geochemistry June 11, 2003 International Summer School on Geothermal Geochemistry

Prof. Dr. Mahmut PARLAKTUNA 11-22 Haziran 2002 PHASE DIAGRAM International Summer School on Geothermal Geochemistry June 11, 2003 International Summer School on Geothermal Geochemistry

Prof. Dr. Mahmut PARLAKTUNA 11-22 Haziran 2002 PHASE DIAGRAM International Summer School on Geothermal Geochemistry June 11, 2003 International Summer School on Geothermal Geochemistry

Prof. Dr. Mahmut PARLAKTUNA 11-22 Haziran 2002 STEAM TABLES International Summer School on Geothermal Geochemistry June 11, 2003 International Summer School on Geothermal Geochemistry

Prof. Dr. Mahmut PARLAKTUNA 11-22 Haziran 2002 SCENARIOS International Summer School on Geothermal Geochemistry June 11, 2003 International Summer School on Geothermal Geochemistry

Scenario-1 83.7 % from rock Initially at 260  C hw1 = 1134.9 kJ/kg Vw1 = 1.275610-3 m3/kg Ew1=1.780  105 kJ/m3 After 30 years production hw2 = 1085.8 kJ/kg Vw2 = 1.2513  10-3 m3/kg Ew2=1.7355  105 kJ/m3 Energy produced from water Ew=4452.5 kJ/m3 Energy produced from rock Er=22857 kJ/m3 Total energy Ea= 27309.5 kJ/m3 83.7 % from rock International Summer School on Geothermal Geochemistry June 11, 2003

Scenario-2 12.1 % from rock Initially at 260  C hw1 = 1134.9 kJ/kg Vw1 = 1.275610-3 m3/kg Ew1=1.780  105 kJ/m3 After 30 years production hs2 = 2800.4 kJ/kg Vs2 = 50.37  10-3 m3/kg Es2=1.1193  104 kJ/m3 Energy produced from water Ew-s=166180 kJ/m3 Energy produced from rock Er=22857 kJ/m3 Total energy Ea= 189670 kJ/m3 12.1 % from rock International Summer School on Geothermal Geochemistry June 11, 2003

Scenario-3 91.7 % from rock Initially at 260  C hs1 = 2796.4 kJ/kg Vs1 = 42.13410-3 m3/kg Es1=1.3274  104 kJ/m3 After 30 years production hs2 = 2800.4 kJ/kg Vs2 = 50.37  10-3 m3/kg Es2=1.1193  104 kJ/m3 Energy produced from steam Ew=2080 kJ/m3 Energy produced from rock Er=22857 kJ/m3 Total energy Ea= 24938 kJ/m3 91.7 % from rock International Summer School on Geothermal Geochemistry June 11, 2003

Volume of reservoir to supply a 100 MW power station with steam for a period of 30 years Eelec= 9.46  1016 J Ethermal= 59.46  1016 J (20 % efficiency) Scenario 1 V= 1.7319  1010 m3 Scenario 2 V=0.2494  1010 m3 Scenario 3 V=1.8967  1010 m3 International Summer School on Geothermal Geochemistry June 11, 2003

Temperature measurements International Summer School on Geothermal Geochemistry June 11, 2003

Negative Temperature Gradient International Summer School on Geothermal Geochemistry June 11, 2003

International Summer School on Geothermal Geochemistry Flowing well International Summer School on Geothermal Geochemistry June 11, 2003

International Summer School on Geothermal Geochemistry Closed well International Summer School on Geothermal Geochemistry June 11, 2003

International Summer School on Geothermal Geochemistry Temperature Profiles International Summer School on Geothermal Geochemistry June 11, 2003

International Summer School on Geothermal Geochemistry Well Completion Test Injection of cold wtaer into the wellbore The two main parameters measured Water loss Permeability International Summer School on Geothermal Geochemistry June 11, 2003

International Summer School on Geothermal Geochemistry Water Loss Test International Summer School on Geothermal Geochemistry June 11, 2003

International Summer School on Geothermal Geochemistry Example International Summer School on Geothermal Geochemistry June 11, 2003

International Summer School on Geothermal Geochemistry Pressure Profiles International Summer School on Geothermal Geochemistry June 11, 2003

PRESSURE TRANSIENT TESTING BUILD-UP TEST International Summer School on Geothermal Geochemistry June 11, 2003

PRESSURE TRANSIENT TESTING BUILD-UP TEST Slope is proportional to PERMEABILITY International Summer School on Geothermal Geochemistry June 11, 2003

PRESSURE TRANSIENT TESTING DRAWDOWN TEST International Summer School on Geothermal Geochemistry June 11, 2003

PRESSURE TRANSIENT TESTING DRAWDOWN TEST Slope is proportional to PERMEABILITY International Summer School on Geothermal Geochemistry June 11, 2003

PRESSURE TRANSIENT TESTING INTERFERENCE TEST International Summer School on Geothermal Geochemistry June 11, 2003

International Summer School on Geothermal Geochemistry TRACER TEST A tracer is an identifiable substance that can be followed through the course of a process Tracers Radioactive tracers: NaI, NH4Br, I131, Br82, H3 Chemical tracers: NaCl, CaCl2, Organic Dyes: Fluoresceine, Rhodamine-B, Methylene Blue Conventioanl tracers are identified by conventional analytical methods such as CONDUCTIMETRY, SPECTROMETRY Radioactive tracers are detected by the emitted radiation International Summer School on Geothermal Geochemistry June 11, 2003