The Bulalo Geothermal Reservoir Makiling-Banahao Area, Philippines

Abstract

The Bulalo field, located within the Makiling-Banahao geothermal prospect, is being explored and developed by Philippine Geothermal Incorporated (PGI), a branch of the Union Oil Company of California. During the past four years, twenty-eight wells have been drilled and completed in the Bulalo heat anomaly. These wells have defined a large geothermal reservoir characterized by a high temperature effluent which can be spontaneously produced to generate commercial power. An extensive flow testing program has resulted in the production of over thirteen billion pounds of reservoir effluent. After flashing the steam to atmospheric condit ions, nearly seven billion pounds of produced reservoir fluid have been reinjected into the Eiulalo reservoir. In spite of the large quantity of reservoir effluent that has been produced and reinjected, insufficient testing has been conducted to determine the total commercial power generating capacity of this large liquid-dominated reservoir. The preliminary estimate of generating capacity has led to the current installation of 220 MW. Field development for the installation of four 55 MW units is in progress. initial 55 NV unit is scheduled for operation in July, 1979, with Unit 2 to operate in the fourth quarter of 1979. Continued drilling and production testing up to the initiation of commercial operation will afford periodic reserve updating and confirmation for additional power- generating units. After commercial power generation commences, data will be available to establish a more reliable estimate of the Bulalo Field potential.