Evaluation of Deep Seated Geothermal Resources in Japan: Emphasis on Simplified Reservoir Models

Abstract

Deep-seated geothermal resources are found at depths of about 2,000 m or more, and are expected to contribute to the immediate growth of geothermal power generation in Japan. NEDO conducted a survey to determine the characteristics and evaluate the feasibilfty of utilizing these resources.

In the first phase of the pmject (FY-7992-7998), a deep exploration well, WD-7, was drilled at Kakkonda. In addition, the following studies were conducted: detailed field survey using the exploration well, research on driling techniques under conditions of extremely high temperatures, and investigation of the possibility of utilizing deep geothermal fluids. In the second phase of the pmybct (FY 1999-2000), deepseated geothermal resources in other fields in Japan were evaluated with the numerical simulation technique. Reservoir parameters such as temperature, pressure and penneabiljty were utilized to evaluate the resources in the deep reservoirs. This study aimed to examine various estimation methods of the reservoir parameters and evaluate the potential resoums in the deep reservoirs in most of the geothermal' fiekis in Japan, where no deep exploration wells have been drilled. The exploitation of deepseated geothermal resourns is feasible and highly mmmended in order to immediately increase the output of Japanese geothermal power plants.

This article briefly describes evaluation methods and pmcedures for deep-seated geothermal resources in several fields excluding the Kakkonda field in Japan with emphasis on the simplified reservoir models fmm geological and reservoir engineering aspects.