| Title | Potential Utilization of Idle Wells in Salak Geothermal Field, Indonesia |
|---|---|
| Authors | Riza PASIKKI, Roman STA MARIA, Frederick LIBERT, Colin PETERS, Fathan ABDURACHMAN |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | salak; idle wells, weak wells, low pressure steam, modular power plant |
| Abstract | Commercial operation of Salak Geothermal field was started in February 1994 when the first two units (Unit 1 and 2) totaling 110 MW were commissioned by the Indonesian utility company (PLN) to exploit the western side of the field. After exploring the eastern part of the field, four new units (Unit 3 by PLN and Units 4 - 6 operated by Chevron) were put on line in late 1997 that increased the total capacity of the field to 330 MW. Generation was further increased to 377 MW in 2002. Due to natural decline, periodic infill drilling has become the primary tool to meet steam supply demand for maintaining the 110 – 377 MW generation capacities. Currently, there are two groups of idle wells at Salak which are not supplying steam to existing power plants. The first group is weak wells which are not capable of producing steam at commercial wellhead pressure. Those weak wells can only produce steam at lower wellhead pressure and could therefore potentially be used to supply low-pressure (LP) steam. Two cases are being evaluated to assess potential utilization of weak wells: • Use LP Steam to displace high-pressure steam on turbine Unit 4, 5 and 6 to maintain current generation. Currently, 1,010 kilo-pound per hour (kph) of high-pressure (HP) steam is delivered to the 1st stage of turbine, at pressure of 88 psia, to generate 65.6 MW. Early evaluation suggests that 250 kph of LP steam supplied to 6th stage of turbine, at pressure of 35 psia, could replace 120 kph of HP steam. This will eventually reduce generation cost through reduction of drilling make-up wells. • Use LP Steam to increase generation from existing turbine to 70 MW by combining high pressure and low pressure steam. The second group includes the commercial wells that remain shut-in due to nonexistence of surface production facilities. Most of these wells are in remote locations and relatively far from the existing power plants and eventually increase hook-up costs. Availability of modular power generation has opened up the alternative of producing those idle wells and adding electricity generation from Salak field. The goals of this study include evaluating reservoir responses to change of production strategies, appraising the feasibility to modify operations on existing turbines, assessing technologies on modular power generation and eventually to identify if realization of cases above could meet economic thresholds and deliver the necessary return on investment. This paper describes the planned work process and results from preliminary studies on reservoir processes and surface facility design options. |