Airborne Survey by a Helicopter for Evaluation of Geothermal Resources

Abstract

JOGMEC supports the smooth development of geothermal resources in Japan by providing assistance to geological, geophysical, and well-drilling surveys, equity capital or liability guarantees, and information and data on geothermal resources. As of them, we evaluate geothermal potential using airborne survey by the helicopter with the gravity gradiometric method and the time-domain or transient electromagnetic (TEM) method. The Airborne surveys were conducted in Kyushu and Tohoku districts to investigate and evaluate geothermal resources, where many geothermal power plants are located. The investigation areas of 300 to 500 km2 were selected around the geothermal power plants in both restricts. The gravity gradiometer method measures the spatial difference of the gravity vector, and provides information of much detailed geological structures. As these methods are, however, state-of-the-art techniques, we demonstrated them in the Kuju and Kirishima areas of the Kyushu district, which are relatively high geothermal potential and mature surveyed areas in 2013, followed by the (TEM) measurement. The helicopter-borne survey has an advantage in covering a wide area and in getting a uniform measurement. At the presentation we will show the survey results and discuss on the geothermal potential in the survey areas.