An Overview of DOE-Funded Geothermal RD Programs at the University of Utah

1. An Overview of DOE-Funded Geothermal R&D Programs at the University of Utah Peter Rose and Jeff Hulen Energy and Geoscience Institute at the University of Utah Geothermal Program Briefing Lawrence Berkeley National Laboratory March 16, 2004

2. AGENDA Tracer Technology, Chemical Stimulation, Electrical Geophysics, Two-Phase Flow Measurement���������Peter Rose Geology, Hydrothermal Alteration, Geochemistry, Remote Sensing�..Jeff Hulen

3. Tracing Fluid Flow in Geothermal Reservoirs Peter Rose and Mike Adams Objective: To develop tools for tracing injected fluids and interpreting fluid-flow processes

4. Tracer Technology AccomplishmentsPeter Rose and Mike Adams Liquid-phase tracers Laboratory development and field testing of a family of eight fluorescent tracers for use in high temperature (>300oC) reservoirs Detection limits reduced by a factor of 100 to 40 parts per quadrillion through laser-induced-fluorescence detection The development and demonstration of the use of fluorescent compounds as thermally reactive tracers The evaluation of analytical methods for estimating reservoir pore volume from tracer data Vapor-phase tracers Laboratory development and field testing of several tracers for application in steam-dominated reservoirs Solubility modeling for the interpretation of return-curve patterns Reduction of detection limit by factor of 100 using solid-phase micro-extraction

5. Technology Transfer: Adoption of the Naphthalene Sulfonate Tracers by Geothermal Operators

6. Follow-On Tracer Research Develop adsorptive tracers for characterizing reservoir fracture surface areas Develop and demonstrate two-phase tracers for measuring flow processes in liquid-depleted reservoirs

7. National Laboratory and Industry Collaboration Paul Spielman, Coso Operating Company Mike Shook, Idaho National Energy and Environmental Laboratory

8. Chemical Stimulation of Wellbores and Near-Wellbore FormationsPeter Rose and Mike Adams Objectives: To design and evaluate chemical dissolution agents for use in wellbore stimulation Evaluate the feasibility of using chemical agents for stimulating near-wellbore formations as an alternative to hydraulic and thermal stimulation approaches

9. Chemical Stimulation of Wellbores and Near-Wellbore Formations (Cont.)Peter Rose and Mike Adams Approach: Determine the decay kinetics and reactivity of candidate dissolution agents under conditions that simulate a geothermal environment Strong mineral acids with improved acid inhibition Weak organic acids Chelating agents Conduct wellbore field experiments to verify the laboratory experiment Model the wellbore mineral dissolution process using reactive-transport models and calibrate using field data Develop models of near-wellbore stimulation processes and conduct experiments to verify models

10. Strong University, National Laboratory, and Industry Collaboration Derek Elsworth, Penn State Joe Moore, U of U Carol Bruton, LLNL Karsten Pruess and Tianfu Xu, LBNL Paul Spielman, COC

11. Measuring Two-Phase Flow Rates at Geothermal WellheadsPeter Rose and John Stodt Objective: To design, fabricate and evaluate electrical-resistivity methods and instrumentation for measuring two-phase flow rates (and thereby enthalpy) continuously and in real time at geothermal wellheads

12. Prototype Resistivity Meter Designed and Fabricated by Paul Spielman at Coso Operating Company

13. Controller and Data Logger Designed and Fabricated by John Stodt at EGI

14. Electrical GeophysicsPhil Wannamaker Objectives: Integrated geothermal systems modeling (Karaha-Telaga Bodas andesitic analog) Resolving system structural ambiguities (Dixie Valley single/multi fault controversy) New-generation EM surveying technology brought to geothermal (MT/DC multi-profile array system from mining industry) Objectives (clockwise from top): Cooperative interpretations with EGI staff in geochemistry and structure provided a new view of physical state of the Karaha �Telaga Bodas andesitic systems analog. Particular features are resistive, high-temperature propyllitic �horst� and conductive magmatic chimney. Dense MT/DC array profiling capability of the mining industry brought to geothermal by P.I. Wannamaker for improved resolution. This system has two great advantages: complete response sampling via contiguous bipole layout, and it exploits the complementary resolving capabilities of EM (MT) and DC (pole-dipole) methods. Next-gen system involves multiple simultaneous profiles and additional EM components for better 3-D coverage. P.I. has developed joint inversion capability for imaging with this system. Wannamaker also is facilitating integration of hardware from the large and well-supported seismic data logger community (IRIS/PASSCAL) with tensor MT recording needs to yield low-cost instrumentation for dense 3-D deployments. Dense MT/DC array profiling using new-generation system shows multi-fault model is preferred structural geometry for Dixie Valley system, thus resolving a long-standing controversy. However, no apparent permeable (conductive) zone is associated with Senator Fumaroles. Objectives (clockwise from top): Cooperative interpretations with EGI staff in geochemistry and structure provided a new view of physical state of the Karaha �Telaga Bodas andesitic systems analog. Particular features are resistive, high-temperature propyllitic �horst� and conductive magmatic chimney. Dense MT/DC array profiling capability of the mining industry brought to geothermal by P.I. Wannamaker for improved resolution. This system has two great advantages: complete response sampling via contiguous bipole layout, and it exploits the complementary resolving capabilities of EM (MT) and DC (pole-dipole) methods. Next-gen system involves multiple simultaneous profiles and additional EM components for better 3-D coverage. P.I. has developed joint inversion capability for imaging with this system. Wannamaker also is facilitating integration of hardware from the large and well-supported seismic data logger community (IRIS/PASSCAL) with tensor MT recording needs to yield low-cost instrumentation for dense 3-D deployments. Dense MT/DC array profiling using new-generation system shows multi-fault model is preferred structural geometry for Dixie Valley system, thus resolving a long-standing controversy. However, no apparent permeable (conductive) zone is associated with Senator Fumaroles.

15. Electrical Geophysics (cont�d) Phil Wannamaker Objectives: Capability has been developed to model EM surface measurements due to subsurface changes in electrical resistivity. Numerical simulation cooperation between EGI, Kyushu Univ., SAIC and INEEL resulted in integration of 3D MT/CSAMT reservoir simulation capability to STAR and TETRAD simulators. Oguni example shows possible MT response changes (% app.res.) due to drawdown and injection over 30 years utilizing known properties of the system (J. Pritchett, pers. comm.). Although substantial progress has been made in 3D modeling and inversion, major advances to optimal reliability, depth of exploration, and speed are possible. Novel inversion concepts by P.I. include expanding regularization grid vs depth in accord with EM scaling to increase depth of resolution, and an adaptive definition of damping which stabilizes according to principles of resolution of diffusive EM. Also, the Gauss-Newton parameter step is recognized as the most stable, but is expensive in 3D due to explicit calculation of Jacobians. P.I. developed new concept combining finite difference and integral equations methods to remove this bottleneck, in cooperation with personnel at Baker-Atlas (S. Fang) and Kyushu Univ. (Y. Sasaki). The approach can yield the full Hessian as well, improving inversion convergence further. Inversions can be made against inhomogeneous a-priori information. Comparisons will be made with Newman-Alumbaugh code for Coso MT data set. P.I. Wannamaker combines 20+ years of experience interpreting EM data sets and developing modeling philosophy, with state of the art algorithm development seeing worldwide distribution and implementation. He has developed unique insights to multi-dimensional EM responses. New inversion capability will be applied to donated finite source (CSAMT) data from the Surprise Valley geothermal system, and MT data from Karaha andesitic analog. Multi-profile, fully joint MT/DC array data set donated by mining industry (Battle Mtn area) will exercise full capability of inversion approach. Wannamaker supervises and supports graduate students. We recognize that, as for the mining and oil industries, geophysical survey and interpretation technology for geothermal resource exploration and assessment has become the domain of external service companies. In most cases, they are expected to provide finalized interpretations for the client. Our developments are made with this community in mind. Inversion technology will be public domain, and be ported to desktop and small Beowulf cluster platforms. This is economical but powerful computing affordable by industry. The MT method with which Wannamaker is primarily concerned is the electrical method with greatest depth of exploration, as must be sought to expand the geothermal resource base.Objectives: Capability has been developed to model EM surface measurements due to subsurface changes in electrical resistivity. Numerical simulation cooperation between EGI, Kyushu Univ., SAIC and INEEL resulted in integration of 3D MT/CSAMT reservoir simulation capability to STAR and TETRAD simulators. Oguni example shows possible MT response changes (% app.res.) due to drawdown and injection over 30 years utilizing known properties of the system (J. Pritchett, pers. comm.). Although substantial progress has been made in 3D modeling and inversion, major advances to optimal reliability, depth of exploration, and speed are possible. Novel inversion concepts by P.I. include expanding regularization grid vs depth in accord with EM scaling to increase depth of resolution, and an adaptive definition of damping which stabilizes according to principles of resolution of diffusive EM. Also, the Gauss-Newton parameter step is recognized as the most stable, but is expensive in 3D due to explicit calculation of Jacobians. P.I. developed new concept combining finite difference and integral equations methods to remove this bottleneck, in cooperation with personnel at Baker-Atlas (S. Fang) and Kyushu Univ. (Y. Sasaki). The approach can yield the full Hessian as well, improving inversion convergence further. Inversions can be made against inhomogeneous a-priori information. Comparisons will be made with Newman-Alumbaugh code for Coso MT data set. P.I. Wannamaker combines 20+ years of experience interpreting EM data sets and developing modeling philosophy, with state of the art algorithm development seeing worldwide distribution and implementation. He has developed unique insights to multi-dimensional EM responses. New inversion capability will be applied to donated finite source (CSAMT) data from the Surprise Valley geothermal system, and MT data from Karaha andesitic analog. Multi-profile, fully joint MT/DC array data set donated by mining industry (Battle Mtn area) will exercise full capability of inversion approach. Wannamaker supervises and supports graduate students. We recognize that, as for the mining and oil industries, geophysical survey and interpretation technology for geothermal resource exploration and assessment has become the domain of external service companies. In most cases, they are expected to provide finalized interpretations for the client. Our developments are made with this community in mind. Inversion technology will be public domain, and be ported to desktop and small Beowulf cluster platforms. This is economical but powerful computing affordable by industry. The MT method with which Wannamaker is primarily concerned is the electrical method with greatest depth of exploration, as must be sought to expand the geothermal resource base.