The Tiwi Field: a Case Study of Geothermal Development for the National Interest

Abstract

The commercial potential of the Tiwi field was established in the 1960s by the Philippine Institute on Volcanology, and development by the National Power Corporation (NPC) and Union Oil Company (now Unocal) through its Philippine Geothermal, Inc. (PGI) began in 1972. The OPEC oil price shocks and rapidly growing power demand in the mid-1970s created a critical need to reduce oil imports and add generating capacity, and development at Tiwi was accelerated. Following startup it became apparent that the field was characterized by thin layers of lateral permeability and limited reservoir storage. Subsequently, groundwater entered the reservoir from sites of natural hot springs to the northeast. Generation has since been maintained by shifting production to high enthalpy wells in the western part to the field. stimulations and steam conservation have also helped maintain generation. The field currently provides just over 10% of the power the Luzon grid, averaging about 150 This accomplished with five units operating continuously and one unit in reserve. Generation to date has more than repaid the investment in power plants and steam field, as