Hydrocarbons in Soil Gas as Pathfinders in Geothermal Resource Surveys in Indonesia

Abstract

A surfacegeochemical techniqueutilizing normal paraffin and aromatic hydrocarbons in soil gas has been successfully used as pathfinders in surveysfor geothermal resources in Indonesia.The Dieng field was used to test the technique. Theresult showsthe anomalies to be near and over productivewells. Because productive wells usually lie over upflow zones it reinforcesourhypothesisthat define the upflow of geothermal systems. The aromatichydrocarbon was found near and around productivewells in the southeast quadrant of the Dieng field (Sikidang-Merdada area) but they are more spread more than the The shapeof their anomalyseemto suggest a tendency of spreading into the direction of lower It is thought that the aromatics, which aremuch more solublethan their correspondingparaffins, express at the surface as only of locations of the upflow but also of the outflow of the geothermal system as well. Therefore the combinedparaffin and anomalies, and topography,may be used as an indicator for the direction of the outflow or the flow of the under ground scarcity of the aromatics in the northwest quadrant of the Dieng field (Sileri area) is unique. A hypothesis has been proposed which could explain this unique feature.