Publications

The Awibengkok geothermal field is located on the flanks of the Gunung Salak volcanic complex, 70 kilometers south of Jakarta, West Java. Under a joint operating contract with Pertamina, Unocal Geothermal of Indonesia (UGI) is developing steam production for sales to the Indonesian public utility (PLN) for the purpose of generation of electricity. The field is currently in the first phase of development with commercial production of 110 megawatts of electrical power scheduled to begin in February, 1994.The Awibengkok reservoir is a liquid dominated, dual porosity system set in highly fractured andesitic volcanics. Within the reservoir, the matrix rocks are propylitically altered and characterized by low permeability yet contain the bulk of fluid storage capacity. The fracture network is prolific, with permeability-thickness products in the range of 100,000 - 600,000 millidarcy feet.Ten wells have been drilled starting with the discovery well, Awi 1-1, in February, 1983. All of the first five exploration wells were producers, with an average power potential of four megawatts per well. After determining the magnitude of the fracture permeability through interference and single well transient tests, the wellbore diameter was increased. The subsequent five wells had an average output of 19 megawatts per well with some of the increase being due to increased temperatures in the production zones.The current development strategy utilizes deep injection wells towards the edge of the field with relatively shallow production from the highly permeable interior.