Detailed Surface Structural Mapping of Dieng Geothermal Field, Indonesia

Abstract

Dieng Field is located in Central Java, Indonesia with 63 km2 of Concession Area. Dieng field also known as Vulcan Complex Area. About 47 wells have been drilled to prove potential geothermal resources of this field and able to generate electricity for Unit 1 (1x60 MW). For Unit 2&3 Development purposes, resource assessment has been doing in Dieng Field. including reservoir modeling and evaluation of surface & subsurface structural mapping. Detailed surface structural Mapping is conducted to evaluate surface structural pattern in Dieng field and to reconstruct volcano-tectonic structural play in Dieng Field. Detailed surface structural mapping in Dieng Field consist of 2 phase, pre-survey analysis phase and post-survey analysis phase. In pre-survey analysis phase, structural analysis derived from IFSAR-DEM is conducted. IFSAR-DEM is chosen regarding its spatial accuracy in which up to 8 m. Three steps of IFSAR-DEM structural analysis is conducted, which are IFSAR-DEM interpretation, including hillshade analysis, manually lineament delineation, and digitally extraction lineament; Statistic analysis; and Kinematics analysis. In Post-survey phase, analysis structural data derived from field data is conducted to reconstruct volcano-tectonic structural play in Dieng Field. The result of this study indicated that Dieng Field is located in the NE Flank of Serayu Geanticline which elongated E-W. Structural play in Dieng Field consist of 3 main orientation, which are NW-SE, N-S, and E-W. This structural play is believed responsible to control permeability zone in Dieng Geothermal Field.