Development of an Ultra-high Temperature Distributed Vibration Sensing (DVS) System for Supercritical Geothermal Wells

Abstract

Supercritical Geothermal Power Generation, in which subduction-origin ultra high temperature (400-500 deg-C) geothermal resources is used as a thermal source, is considered as one of the few methods which can contribute to drastic reduction of emission of CO2 around in 2050 in Japan. The government of Japan has initiated national projects to investigate feasibility of the supercritical geothermal power generation. Downhole monitoring of acoustic signals is of critical importance for management of naturally existing/artificially created fracture system inside the supercritical rock body, because we expect a presence of fracture network with a grain scale in the supercritical rock body and energy of acoustic signals from seismic activity would be very small. The authors designed and manufactured a ultra-high temperature distributed vibration sensing (DVS) system in a METI project and successfully demonstrated that the system has an ability to detect vibration applied to fiber under 500 deg-C conditions in laboratory.