Geoscience
Learn what the National Laboratories are doing to assist the geothermal industry by optimizing field development and management, and providing more accurate and comprehensive simulation capabilities that incorporate geochemical and geophysical information.
- Geophysical Measurements for Fracture Detection
- Reinjection of Chemically Modified Geothermal Brines
- Improved Geothermal Reservoir Management
- Solubility and Phase Equilibria of Fluorocarbon Tracers
- Tracer Test Interpretation Methods for Reservoir Properties
- Structural Geology and Geophysics at Dixie Valley, Nevada
- Studies of Geothermal Reservoir Dynamics
- Geophysical Methods for Resource Exploration and Monitoring
- High Temperature Instrumentation and Tools
- University Research Grants
- Enhanced Geothermal Systems (EGS)
Geophysical Measurements for Fracture Detection
Organization: Lawrence Livermore National Laboratory
LLNL is developing methods to measure the fracture or crack density within a geothermal field, and the direction to fractures several meters from a borehole. We will complete the testing of the GEO-BILT electromagnetic logging tool that will produce valuable three-dimensional information about lithology and the nature of reservoir fluids, and orientation of permeable zones within several meters of a wellbore, can be inferred. This will require a field demonstration, probably at Dixie Valley, and analysis and publication of the resulting data. We will continue to conduct laboratory studies of intact and fractured geothermal rocks at reservoir conditions to demonstrate how electrical anomalies can be used to locate zones of high fluid permeability. The time-dependence of resistivity change will be modeled with a multi-phase code such as NUFT or Tetrad. We will attempt to apply the results to available field EM surveys, and to data collected by the GEO-BILT tool.
Reinjection of Chemically Modified Geothermal Brines
Organization: Lawrence Livermore National Laboratory
We are starting a new modeling and field study to evaluate the effect of injection of chemically modified fluids on the geothermal reservoir and on injectivity over time. Examples of significant issues related to reinjection are as follows: Although rock is an efficient buffer, what components are added to the fluid when the most soluble minerals dissolve? Is the solution composition changed? Are toxic elements leached from the rock that will cause problems if produced later? If the rocks are iron-rich, could iron be released and re-precipitate to drastically clog permeability? How does the reduction in porosity/permeability from silica precipitation balance the potential increases from mineral dissolution, if they occur in the same locale at all? Is reduced reinjectivity due mainly to wellbore precipitation, or reactions in the formation? Recent work also suggests that injection of chemically modified brines can affect the strength of rocks, and induce subcritical cracking over time. Our first phase is a literature study on experiences of injection related to the features of the field in question. As part of this study, we will contact producers to identify and document outstanding reinjection problems at several geothermal sites. We will then carry out reactive transport simulations to model injection and the chemical and physical reactions between the injected fluid and aquifer minerals. These models will allow us to identify critical reactions controlling scaling and changes in permeability, and investigate possible intervention techniques. This work will be used to define laboratory and field tests in the out-years.
Improved Geothermal Reservoir Management
Organization: Idaho National Laboratory
The large capital investment for geothermal development requires careful management of both reservoir production and power plant operation to sustain resource production and optimize electrical generation. Reservoir management, power plant operations and time related sales price can be jointly optimized to obtain various short and long term economic goals and resource sustainability. The purpose of this project is to investigate relationships between reservoir production, power plant operation and pricing to determine scenarios for geothermal production. The project will consist of field studies with tracer tests and analysis of the tests. The study will also compare baseline operations of an existing Basin and Range binary plant against optimized operations to demonstrate improved resource management.
Solubility and Phase Equilibria of Fluorocarbon Tracers
Organization: Idaho National Laboratory
This study will evaluate candidates for applicability as geothermal tracers by providing physical property data of candidate fluorocarbon tracer compounds in water and geothermal brine. This data will be used in: a) determining the candidate compounds' utility as a geothermal tracer and b) measuring properties necessary for predicting their transport properties. The study will examine thermal stability of tracer chemicals, measuring solubility and phase partitioning of fluorocarbons in high temperature geothermal fluids and compare the data with theoretical predictions. In addition, thermodynamic constants for standard EOS models will be determined.
Tracer Test Interpretation Methods for Reservoir Properties
Organization: Idaho National Laboratory
The purpose of this project is to develop tools that can be used to interpret tracer tests and obtain estimates of reservoir and operational parameters. These tools (mostly in the form of spreadsheet applications) will be developed from an examination of energy and mass conservation equations, and can be used to optimize geothermal resource management. The "tool kit" of interpretation tools will include tools for either heterogeneous permeable or fractured media, for either single- or two-phase flow application.
Structural Geology and Geophysics at Dixie Valley, Nevada
Organization: Idaho National Laboratory
This research is undertaken to develop a greater understanding of the subsurface geometry of faulting in the region surrounding the geothermal reservoir at Dixie Valley, NV by merging the field observations with available geophysical data and borehole information. The study will generate a detailed structural geologic map of the region surrounding the reservoir and provide geological interpretations and conceptual modeling of the area. The resulting conceptual model will be used as a basis for further exploration in Dixie Valley and in the Basin and Range province in general.
Studies of Geothermal Reservoir Dynamics
Organization: Lawrence Berkeley National Laboratory
Reservoir simulators include only rudimentary capabilities for chemical transport and rock-fluid interactions. To optimize field development and management, industry needs more accurate and comprehensive simulation capabilities that can incorporate geochemical and geophysical information. Work Scope: Apply and enhance LBNL's simulation codes TOUGH2, iTOUGH2 and TOUGHREACT to model the behavior of noble gases and other phase-partitioning tracers, and rock-fluid interactions during production and injection operations. Develop post-processing routines for predicting geophysical signatures of reservoir conditions and processes. Study the visibility of hypothetical "hidden" geothermal fields. To enhance production, wastewater is pumped to The Geysers geothermal field, some from the Clear Lake area and more from Santa Rosa (starting in 2002). Optimal use of this imported water requires understanding of the behavior of a vapor-dominated reservoir when the volume of injected water is substantially increased. Work Scope: Geochemical, isotopic, flow, and enthalpy data, mostly provided by Calpine Corp. (in collaboration with Joe Beall), will be analyzed to better understand the properties of the high-temperature reservoir fluids and the effect of limited injection. Provide technical assistance to US industry, trade organizations, DOE's Office of Wind and Geothermal technologies, and other federal, state, and local agencies in activities related to the evaluation and development of high- and low-temperature geothermal systems; to include assisting in the evaluation of proposals and plans, participation on technical panels, workshops, and meetings, and the transfer of DOE-funded technologies.
Geophysical Methods for Resource Exploration and Monitoring
Organization: Lawrence Berkeley National Laboratory
The extreme heterogeneity, anisotropy and mixed fluid phases found in many geothermal areas pose significant challenges for "conventional" seismic imaging technology. Needed is an extension and adaptation of current methodology to optimize state-of-the-art multi-component 3-D and 4D seismic imaging methods for geothermal application. There will be three principle activities: (1) 3D modeling of elastic wave propagation in fractured/heterogeneous reservoirs, (2) integration of seismic methods, and (3) data processing and interpretation. We will use an iterative approach between each activity, leading to an overall refinement of seismic imaging methods. Electromagnetic Instruments Inc. (EMI) has been developing new high-temperature (>250° C) borehole electromagnetic (EM) tool for geothermal exploration. It is anticipated that the new device, termed Geo-BILT (Geothermal Borehole Induction Logging Tool), will provide high-quality 3D EM data in a single-borehole environment. Development of imaging methods is an integral part of the overall goal of the borehole EM technology for geothermal applications. We will investigate an approximate inversion scheme for analyzing 3D electrical structures in the vicinity of a borehole. The inversion scheme is essentially an extension of the modified Born approximation, but it has been reformulated to handle 3D electrical structures in single borehole environment. EMI had the Geo-BILT tool field tested in May this year, and it will be further tested in Dixie Valley (Sept. & Oct.) and the Geysers (Oct. & Nov.) in 2001. The tool is equipped with three-component sources, and three-component magnetic sensors at two offset positions. This unique capability offers full 3D EM data in a single borehole environment.
High Temperature Instrumentation and Tools
Organization: Sandia National Laboratories
Logging (downhole measurements from within a geothermal wellbore) is generally required during drilling, during reservoir evaluation, and during production. The individual projects that comprise this activity address all these issues.
Task 1 - Having made the discovery that eliminating phosphorus from the optical fiber greatly reduces degradation in geothermal wells, we plan to set up a long-term test in a production well at Dixie Valley. We also plan to test and evaluate a new surface-electronics unit, built by SPEC of Austin TX, used to make the measurement in the fiber.
Task 2 - We will consult with and advise Thermochem on building and testing the improved liquid-sampler tool.
Task 3 - PhotoSonic will supply logging tools and support personnel. Sandia will supply the logging equipment and calibrated Pressure/Temperature/Spinner (PTS) tools for comparison. The Sandia PTS tool will be used to benchmark the performance of the PhotoSonic tool. The results will be analyzed for accuracy and/or weaknesses.
Task 4 - We will evaluate the feasibility of upgrading the USGS televiewer to operate at 300OC and, if it appears feasible, will assist the USGS with the modification.
University Research Grants
Project Manager: J. Nathwani, (303) 275-4756
Organization: DOE Golden Field Office
In order to broaden the scope of reservoir engineering and geoscience research in the geothermal program and to entertain new and novel research approaches, DOE requested proposals for research over several years. INL monitors technical performance and collects, integrates, and disseminates information from the research grants. DOE and INL will develop a research and development plan based on peer review reports and programmatic objectives. DOE will issue a new solicitation to include high-risk EGS related research projects. DOE and INL will analyze and realign the R&D portfolio with programmatic and technical objectives. INL will organize and, in conjunction with University of Nevada Reno, host a geoscience-related workshop for Dixie Valley.
Enhanced Geothermal Systems (EGS)
Organization: DOE Idaho Operations Office
Ultimately, this will lead to an increase of the electrical power from geothermal resources. New, viable, and geographically diverse geothermal resources are a most critical aspect for bringing more geothermal kilowatts on line. DOE-ID will select one from the Phase II participants who will continue development of field projects to verify EGS technology. INL will provide technical oversight, management, and reporting of the Enhanced Geothermal Systems awards. SNL will assist INL as requested to ensure adequate review of proposals received under the EGS solicitation and proper oversight of the EGS projects. One of the Phase II projects will be selected for continuation funding that will lead to Phase III, field validation of EGS technology. DOE-ID will issue a second EGS solicitation to test an EGS system not associated with existing production.