Present Status and Tasks of the Ogachi HDR Project

Abstract

The CRIEPI's Ogachi HDR Project has begun in 1989 with the objective of developing elemental technologies to make economically available geothermal energy. Two reservoirs, the upper and the lower, were created by drilling of a 1,000m well (the injection well) and by hydraulic fracturing in the basement rock of granodiorite at Ogachi, in Akita Prefecture, Japan. In 1993, another well (the production well) with a 1,100m depth was drilled intersecting both of these reservoirs. After two circulation tests and some reservoir stimulations using these two wells from 1993 to 1995, a one month circulation test was conducted in 1995 and hot water and vapor of 165°C were produced at a rate of7.5m3/hour from the production well when water of 20°C was injected at a rate of 30m3/hour from the injection well.

These accomplishments have been supported and paralleled by developments in various technologies such as the microseismic fracture mapping technique, the multiple-reservoir creation technique, the geology and geochemistry studies, and many instruments to obtain hydraulic and thermal data etc.

The most important task for the next step at Ogachi is the evaluation of the reservoir by some data analyses and a 3D-simulation method.