Abstract

The Awibengkok geothermal field is a liquid dominated reservoir located on the western flank of the Pleistocene to Recent Gunung Perbakti-Gagak volcanic complex, West Java. Commercial generation of 110 MWe began in April 1994 and the field is currently being expanded to 330 MWe to be on line by late 1997. The wells encounter high temperatures (225-310 °C) and relatively benign fluids. Reservoir rocks consist of propylitically altered intermediate to silicic pyroclastic rocks and flows. The hydrothermal alteration is in equilibrium with the reservoir fluid chemistry. Well flow tests show high reservoir permeability, favoring large diameter well completions. The reservoir model demonstrates that the field can sustain 330 MWe over the 30-year contract life. The development strategy is to produce from the shallow central region and to inject deep on the edge of the system. A total of 50 wells, which includes all existing wells, will be required at the start-up of the new power plants. Well locations have been selected in order to maintain separation between injection and production wells, and to minimize pump use to the injection sites.