Manito Lowlands:The First Low-Enthalpy Field Under Exploitation in the Philippines

Abstract

The Manito Lowlands is a low-enthalpy field situated at the outflow of the main geothermal reservoir of the Bacon- Manito Geothermal Production Field. Exploitation commenced in October 1998 with the inauguration of the Manito Geothermal Livelihood Project (MGLP), comprising of a 1.5 MWe pilot power plant and a multi-crop drying plant. This undertaking was pursued by the government to help the marginalized communities by providing cheap electricity and crop drying facilities. Three medium-depth wells were drilled in the early 80ís which produced low-enthalpy fluids. Highest temperature recorded was 227oC, lower compared to 326oC in Palayan- Bayan. Only MO-2 yielded neutral discharge fluids suitable for industrial application. The well was shut when it was affected by calcite deposition. It was reconsidered recently as a production well and was worked-over to remove the blockage. MO-4R was drilled as an injection well for the separated brine. The primary field management problem is calcite deposition in MO-2 which is addressed through mechanical work-over. Well parameters, resistivity data and temperatures were used to determine the capacity of the low temperature reservoir. Prospects for further development of the field are under evaluation.