1. 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

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

9. 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

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

11. 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

12. 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

13. 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

14. 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

15. 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

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

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

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

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

20. 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=  1010 m3
Scenario 2
V=  1010 m3
Scenario 3
V=  1010 m3
International Summer School on Geothermal Geochemistry
June 11, 2003

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

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

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

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

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

26. 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

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

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

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

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

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

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

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

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

35. 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