The National Geothermal Exploration Technology Program

In response to the Geothermal Energy Research, Development, and Demonstration Act of 1974, a federal geothermal program has been established with the objective of stimulating the commercial development of geothermal resources. The program goal is to increase the annual rate of energy utilization from the present 0.04 quads (500 MWe) to 0.3-0.5 quads in the near term (about 1985), 4.0-9.0 quads in the mid-term (1985-2000), and 16.0-28.0 quads in the long term (by about 2020). The realization of these goals depends upon the discovery and exploitation of many new geothermal resource areas.The Department of Energy program for geothermal exploration and assessment has been structured to address technological barriers presently hindering the economical discovery and delineation of geothermal resources. We describe the program elements--exploration technology, reservoir assessment, reservoir confirmation, and reservoir engineering--in light of the need to evaluate some 1500 new prospects in order to meet the federal midterm electric power goal of 20,000 MWe on-line by the year 2000.We illustrate the program elements with suggested sequences for exploration, assessment, and confirmation of a 200-MWe resource in the eastern Basin and Range physiographic province. The estimated costs for these sequences are $385,000, $565,000, and $3,190,000, respectively. Deep drilling constitutes the major element in the confirmation costs.An economical exploration strategy requires use of cost-effective techniques; thus, we have initiated a number of technology assessment studies. Pursuant to these studies, we present a summary of our initial findings and discuss the status and needs for topics such as system modeling, thermal methods, rock and fluid properties, seismic, and electrical methods.Accurate reservoir assessment requires new developments in logging instrumentation for high-temperature, hostile environment boreholes and improved means for interpreting acquired data. The logging instrumentation program is aimed at upgrading logging systems for operation at 275 degrees C. and 48.3 MPa in the near term (1982) and 350 degrees C and 138 MPa by 1986. Existing hardware is being upgraded, components and materials are being developed, and critically needed prototype tools for temperature, flow, and pressure measurements will be evaluated.A program addressing log interpretation problems uses industrial expertise to analyze specific shortcomings in our ability to infer critical reservoir parameters from acquired data. The program will also establish and maintain test and calibration wells and support research logging and petrophysical studies.