Field Management Strategies for the Development of the Northern Negros Geothermal Field, Philippines

Abstract

The Northern Negros Geothermal Field in the northwestern slope of Canlaon Volcano, Negros Occidental province, Philippines is a high temperature (290oC) liquid-dominated geothermal system with an upflow region southeast of the presently drilled sector and a major outflow towards the northwest. The heat source is associated with volcanism at a post-Canlaon caldera eruption center (Hardin Sang Balo) 3 km south of the main production pad. Reserve estimates predict a potential resource of 42-63 MWe for the field, which the Philippine National Oil Company - Energy Development Corporation will develop into a 40 MWe power project.

Developing the field presents major field management issues to be addressed. Production wells drilled are constrained within a limited area inside the geothermal reservation and outside the national park that exploit the upflow region while respecting environmental and socio-cultural interests. Drilling the production wells to the desired targets is difficult and discharging these wells requires stimulation methods such as airlifting and acidizing. Wells tested have indicated possible significant pressure drawdown and well interference during exploitation. Furthermore, the high potential for calcite deposition calls for novel solutions such as periodic acidizing and calcite inhibition. Figure concentrated temperatures known 2.0.

Implementation of the strategies discussed is underway in preparation for the commercial operation of the power project by year 2006.