Transient Electromagnetic Survey Using HTS-SQUID Sensor in the Ogiri Geothermal Field, Southwestern Japan

Abstract

Japan Oil, Gas and Metals National Corporation (JOGMEC) is conducting heli-borne surveys for several geothermal fields in Kyusyu and Tohoku areas to acquire a fundamental geophysical data and to contribute future geothermal development. The survey includes a transient electromagnetic (TEM) method to measure a resistivity structure of those geothermal fields. In order to verify the data quality, we acquire a ground-based TEM data in the survey areas using an TEM survey equipment with the high-temperature superconducting interference device (HTS-SQUID) magnetometer, which is originally designed and manufactured in JOGMEC and is named SQUITEM. There is no precedent for SQUITEM survey in Japanese geothermal field, which is usually located in a mountainous region, and therefore operational impracticability is concerned. The SQUITEM survey is conducted in the Ogiri geothermal field not only for the validation of heli-borne EM data but also for the demonstration of the efficiency of this method with the SQUITEM. This paper introduce the SQUITEM survey project around the Ogiri geothermal field.