Geothermal Exploration Technologies Overview in the U.S.

1. Geothermal Exploration Technologies February 15, 2012 Webinar Energy Efficiency & Renewable Energy Energy Efficiency & Renewable Energy eere.energy.gov

2. Geothermal Exploration Technologies Webinar Agenda 10:00 am Welcome Randy Manion, WesternArea Power Administration 10:05 Opening Remarks Tim Reinhardt, US DOE Geothermal Technologies Program 10:20 Exploration Technologies and Their Applications, Paul Brophy EGS 11:00 Q&A 11:30 Adjourn Energy Efficiency & Renewable Energy eere.energy.gov

3. Hydrothermal and Resource Confirmation Webinar Tim Reinhardt Office of Energy Efficiency and Renewable Energy U.S. Department of Energy Energy Efficiency & Renewable Energy eere.energy.gov

4. Opportunity • 30 GW • of undiscovered resources • The USGS estimates there is a mean of 30 GWe of undiscovered hydrothermal in the 13 western states • Once confirmed, these resources can be brought online with existing technologies Ref. USGS 2008 4 Energy Efficiency & Renewable Energy eere.energy.gov

5. Challenges The exploration phase of geothermal development is a risky financial venture Some resources show no surface expression, making them difficult to confirm Low price of competing energy sources Challenges, Approach and Goal • Approach • Conduct research and development to lower geothermal risks and costs. • Goal • Lower the levelized cost of electricity for blind hydrothermal systems to 6 ¢/kWh by 2020. Maui, Ormat Source: Sierra Geothermal Power Glass Buttes, Ormat Source: Sierra Geothermal Power Silver Peak, Sierra Geothermal 5 Energy Efficiency & Renewable Energy eere.energy.gov

6. Geothermal Exploration Technologies- How and where are they being used in the U.S. by Paul Brophy EGS Inc. Santa Rosa, CA US DOE Geothermal Technologies Program Webinar February 15, 2012

7. Webinar Overview • Basics of Geothermal Energy • Remote Sensing • Geology • Geophysics • Geochemistry • Geothermics • Conceptual Geologic Models • Summary

8. Geothermal Resource Types • Conventional Hydrothermal (Geothermal) Systems • Liquid/Vapor dominated (electric power) • Direct Use (space heating, industrial processes) • Earth Heat Systems • Engineered Geothermal Systems (EGS)(electric power) • Geothermal Heat Pumps (residential heating & cooling) • Deep Sedimentary Basins (electric power, direct use) • Oil & Gas Wells, Co-production (electric power)

10. Basics of Geothermal Energy

11. Steam Cap Deep Liquid Reservoir Hypothetical High-Temperature Hydrothermal System

12. Geothermal Regions and Favorability K. Young 2012

13. Key Exploration Questions • What is the Resource Temperature? • What is the Resource Depth? • What is the Resource Quality? • How large is the Resource (Area Extent)? • How Productive are the Wells? • What are the estimates of Resource Longevity?

15. Exploration Approach • Remote Sensing Data • Geologic Mapping and Surface Manifestations • Structural Setting • Geochemical Sampling and Analysis • Geophysical Surveys • Exploration Drilling • Temperature Gradient/Heat Flow • Exploration (Core) Wells • Production Well Drilling

16. Remote Sensing • Information obtained: • Surface features (vegetation, mineral, thermal properties) • Techniques and tools: • Satellite and airborne imagery (multi-spectral, hyper-spectral, radar, thermal infrared, InSAR…) • Aerial surveys (imagery, LiDAR)

17. Satellite and Airborne imagery Cotopaxi Volcano, Ecuador Colima Volcano, Mexico

18. Aerial surveys: LiDAR Big Sur, CA

19. Geology and Structure • Information obtained: • Surface and subsurface lithologies • Structural framework – stress and strain relationships • Alteration mineralogy • Localize possible permeable zones • Techniques and tools: • Geologic mapping • Thin-section alteration mineral recognition • Exploration core well

20. Geologic and Structural mapping

21. Thin-section alteration mineral recognition Actinote, Calcite, Epidote and Garnet

22. Exploration Core Well – Core Samples

23. Structural Analysis • Regional Structural Analysis • Regional Seismicity, • Stress Field Determinations • Geometry of Fracture systems • Fault Kinematics • Slip Tendency Analysis

24. Surface Geophysical Techniques For Permeable Geothermal Systems • Common (sometimes justified) assumptions • Routine:MT is the default method, especially for >1000 m • Common: Gravity to define basin faults and trends • Reflection seismic if quality is likely to be good and structure can be usefully imaged • Temperature Gradient Holes • Case by case: TEM, T-MT, AMT, VES, DC-T, HEM • Gravity, SP, Refraction seismic • Aeromagnetics, Precision Ground Magnetics • Legacy: Dipole-Dipole, Roving Dipole • Development: Microgravity, Microearthquake, Subsidence

25. MT Method Alteration Clay Alteration • 1 Hz is about 1 km down • Shallow features like surface alteration result in different resistivity on Ex and Ey dipole. This is called static distortion. • Ex, Ey 2 dipoles ~100 m • Hx, Hy, Hz 3 magnetometers • EM signal from sun and electrical storms • Solar signal sometimes low Cumming Geoscience

26. 2-D Magnetotelluric data

27. Seismic techniques Seismic survey at Borax Lake, OR

28. Airborne Magnetics (Portland area)

29. Gravity data

30. Seismicity

31. Geochemistry • Information obtained: • Fluid source • Heat source • Subsurface temperature • Fluid flow path and history • Fault location • Techniques and tools: • Fluid Analyses (Chemical and isotopic composition) • Geothermometers • Fluid Inclusions • Tracers • Gas concentration mapping (CO2, Hg)

32. Fluid Analyses

33. Geothermometers

34. Fluid Inclusions

35. Gas concentration mapping

36. Geothermics • Information obtained: • Temperature distribution • Fluid temperature • Techniques and tools: • Heat flow • Shallow Temperature survey • Temperature gradient holes • Temperature model

37. Heat Flow

38. 2-meter temperature probes

39. Temperature Gradient Holes TG Holes

40. Anomalies or Conceptual Modelsfor Drill Target Selection • An old approach for selecting drill targets would be to pick one or two of the most significant (or preferred) anomalies from project exploration data. • More recent approach would be to look at overlapping anomalies from the data sets for well targeting. • Today most explorationists would integrate geology, geochemistry, geophysical and geothermic data into a comprehensive geothermal conceptual model and “drill the model”.

41. Temperature Models

42. Generic Geothermal Conceptual Model >200°C <200°C

43. Exploration Summary • Context is critical • Extreme variability • Limited resource models • What are you testing? • Anomalies • Geologic concepts • No simple formula • Setting dictates methodology • (see context above) • Target : Upflow • Permeability control(s) • Progressive exploration • Geology • Geochemistry • Geophysics • Geothermics • Shallow/Intermediate/Deep Paul Brophy EGS Inc. Email: pbrophy@envgeo.com

44. Future Potential GTP Webinar Series Topics • Geothermal Power Plant Operation and Maintenance • Geothermal Low Temperature Conversion Technologies • Geothermal Potential on Tribal Lands • Geothermal Power Permitting on Federal Lands • Utilities’ Roles in Geothermal Energy Development • Geothermal Technologies Program support of development in the US and abroad • U.S. Geothermal Market Expectations and Trends • Geothermal Developer Perspective • Geothermal Project Case Studies Please provide feedback to Randy Manion manion@wapa.gov Energy Efficiency & Renewable Energy eere.energy.gov