SLIMHOLE DRILLING: MARICABAN ISLAND (TINGLOY) LOW-ENTHALPY GEOTHERMAL PROSPECT

Abstract

The Maricaban Island (Tingloy) geothermal prospect was one of the three candidate areas for the Department of Energy’s (DOE) locally-funded project: “Detailed Resource Assessment of Selected Low-Enthalpy Geothermal Areas in the Philippines”, implemented from January 2011 to June 2015. The result of the integrated resource assessment for the area suggests a Cl-rich reservoir based on the chemistry of the thermal springs. To further investigate the occurrence of the reservoir, two slimholes with an accumulated depth of 1,500 m was drilled in the area using tractor mounted core drilling rig. The data collected from the two slimholes shows a steeply dipping sedimentary rock formation overlaying the probable reservoir. From the two slimholes, hot water has flowed at an approximate rate of 1 L/s while there was no flow but a standing column of water was encountered at the second well. In a short period of time the slimhole drilling was completed due to the prevalent lithology of these sedimentary units. The highest recorded temperature for both slimhole ranges from 130-136?C.