Investigation of a Reinjection Geothermal Water Flow by the Activable Tracer Method and the Application of a Tracer Model

Abstract

Several wells have been drilled for a planned geothermal power station in a geothermal area of mid-Kyushu, Japan. Yet the area is only a few kilometers away from hot spring resort, the influence of the production and reinjection of geothermal fluid to natural hot springs need to be investigated. Tracer test have been done using the activable tracer Dy-DTPA. As a preliminary investigation, lkg Dy-DTPA was injected from a reinjection well, and it Has sampled at surrounding four production wells and five hot springs once a week for about a month. The breakthrough of the tracer was observed almost at every sampling point. From the analysis of tracer concentration variation, following conclusions might be drawn out(cf., fig):