Reservoir assessment of the southeast sector of the Kamojang geothermal field, Indonesia

Abstract

A general description is given on the southeast sector of the Kamojang geothermal field. It is assumed that there is a low-permeability barrier separating the sector from the main production field. Evaluation of formation temperatures and pressures is carried out from 175 downhole measurements. A conceptual reservoir model is presented, suggesting a vapour dominated reservoir of 240-246°C initial temperature and 35-37 bars initial pressure. The reservoir is around 1 km thick and overlain by 500-1000 m thick liquid saturated caprock. The southeast sector of the Kamojang field appears to be 2-4°C hotter than the main wellfield, suggesting either the existence of an upflow zone or a low permeability volume. Volumetric assessment for the southeast sector of Kamojang suggests a power potential of 9.5 MWe per km2 of the wellfield. Estimating the reservoir area to be 1.5-2.5 km 2 gives 14-24 MWe in total. On the other hand, by using the Monte Carlo statistical approach, a 15-30 MWe reserve estimate is obtained for the wellfield.