DELINIATION OF PROSPEST AREA AND RESERVOIR STRUCTURES OF JABOI GEOTHERMAL AREA AS MAPPED FROM RESISTIVITY DATA

PROCEEDINGS JOINT CONVENTION BALI 2007
The 32^nd HAGI, The 36^th IAGI, and The 29^th IATMI Annual Conference and Exhibition

DELINIATION OF PROSPEST AREA AND RESERVOIR STRUCTURES OF JABOI GEOTHERMAL AREA AS MAPPED FROM RESISTIVITY DATA

Edi Suhanto and Kasbani¹

¹Geothermal Research Group
Center for Geological Resources – Agency of Geology
Jl. Soekarno Hatta No. 444 Bandung
Email: edi _suhanto@dim.esdm.go.id, kasbani@dim.esdm.go.id

ABSTRACT

Jaboi geothermal area, located in the southern part of Weh Island, is one of the most interesting geothermal areas in Nanggroe Aceh Darussalam. Surface thermal features in the Jaboi area consist of fumarolas, solfataras, hot grounds, hot springs, and ground alterations. We conducted dc Schlumberger resistivity measurements in the Jaboi area in 2005, as one of the detailed surveys for the assessment of geothermal resources in the area. We applied current spacings of AB/2 until 2000 m for sounding measurements with number of measurement sites was 52. The results show a pronounced low resistivity zone delineated the prospect zone of the area of about 20 km². Patterns of lateral resistivity distribution describe outflow zones of the field to extend to Jaboi and Keuneukai hot spring manifestation areas. Resistivity structures indicate a clay-rich conductive layer form a dome-like structure with its top close to surface beneath Jaboi fumarola area. Thickness of this conductive layer varies from about 200 m beneath the fumarola to more than 1000 m beneath the outflow zones. Pattern of this Jaboi resistivity structure is similar to the typical resistivity structure of high temperature geothermal systems in volcanic areas.

Keywords: dc resistivity method, prospect zone, conductive layer, Jaboi, Aceh, geothermal resources.