Structural Controls on the Occurrence of Acid Zones in the Lagunao and Balas-Balas Sectors of the Palinpinon Geothermal Field, Negros Oriental, Philippines

Abstract

Shallow to deep acid zones characterized by the presence of alunite, kaolinite, dickite, pyrophyllite and diaspore were encountered by the wells drilled in the Laguna0 and Balas-balas sectors of the Palinpinon Geothermal Field. Some of these zones are related to the faults that were intersected b.y the wells. Some of these acid zones are cased-ogand isolatedpom the open-hole section ofthe well, preventing the acid fluids to enter the well and cause acid discharge. Some of these zones, however, were intersected at the open sections qfthe well and cause acid discharge. The present slrategv in developing these sectors is to intersect the identified acid faults at much deeper elevations where the geothermal fluid is of neutral pH.