Multiple Reservoir Creation and Evaluation in the Ogachi and Hijiori HDR Projects, Japan

Abstract

It is necessary to create and evaluate multiple reservoirs for extracting heat effectively from Hot Dry Rock (HDR) geothermal development. In the Ogachi HDR project, two reservoirs were created at different depths from one 1,000 m deep injection well and one production well was drilled to penetrate the two reservoirs. Two reservoirs were also created from two 1,800 m deep and 2,200 m deep injection wells and two production wells were drilled to penetrate the two reservoirs in the Hijiori HDR project. Unbalanced water flow in the two reservoirs of the projects was occurred after some hydraulic stimulation operations. Particularly, unbalanced water flow resulted in scaling problems during water circulation in the Hijiori. In this paper, the Ogachi and Hijiori projects were reviewed and effective heat extraction system from multiple HDR reservoirs were discussed.