Geothermal Fluid Flow System in the Otake Field

Abstract

The Otake Geothermal Power Plant is located in Kyushu Island, Japan. The plant stwed commercial operation in 7967 and has maintained a power output of 12.5MW. The flow pattern of the geothermal fluid in this field has been conceptualized based mostly upon the analysis of geological and geochemical data, but no numerical simulation was attempted. We went a step forward in studying and determining the behavior of flow pattern of the geothermal fluids in the Otake field by means of natural state and history matching calibrations.

From our study of available data, we interpreted that the geothermal fluid is being heated at depth around Mt. Kuroiwa, and that it migrates along the Sujiyu and the Hizenyu faults, to be stored in a mushroom-like reservoir in the Otake area. Similar flow systems could be numerically reproduced, leading us to the conclusion that the model is adequately calibrated to perform the quantitative management of the reservoir exploitation.