Reservoir assessment of the Mak-Ban geothermal field, Luzon, Philippines

Abstract

The Mak-Ban geothermal field has been under commercial operation since 1979. The National Power Corporation (NPC) produces bulk electricity from its 330 MWe geothermal power plant complex with the Philippine Geothermal, Inc. - Union Oil of California (PGI-UNOCAL) as steam field operator. It is one of the major base-load power plants in the Philippines and contributed 10% of the country's total energy requirements from 1980-89. It is also a reliable plant and achieved the best plant factor of 80% for all power generating plants during the same period. In this report, an attempt is made to assess the extent and nature of the Mak-Ban geothermal field. By using three different reservoir assessment methods, i.e. volumetric, lumped modelling, and in-situ boiling to available field data, the generating capacity of the field for 30 years was estimated and predictions made for the pressure drawdowns for different production rates in the future. According to this assessment, the Mak-Ban reservoir will supply steam for the current installed plant capacity of 330 MWe for at least 30 years, or up to 2010, as the plant has already been in operation since 1979.