The Resistivity Model of the Mindanao Geothermal Project, South Central Mindanao, Philippines

Abstract

Latest MT data of the Mindanao Geothermal Production Field (MGPF) delineated a NW-trending MT anomaly characterizing the shallow electrical basement between the western flanks of Mt. Apo and eastern slopes of Mt. Zion. This is inferred to represent the extent of the high-temperature resource (>300oC) at MGPF. The northeastern segment of the MT anomaly is located within the Sandawa Collapse, where several producing wells have been drilled. On the other hand, the southeastern extension of the anomaly is still untapped and covers the area beneath Mt Zion, Lake Macadac and the southern slopes of Mt. Apo.
The ~6 km2 to the southeast outside of the Sandawa sector is estimated to have a potential to produce about 170 MWe increasing the exploitable resource at MGPF to ~460 Mwe total reserves.
The <30-&#61527;-m conductive zones located around the MT anomaly signify the most likely outer margins of the resource. The prominent low resistivity region mapped in the northwest depicts the major outflows towards Agco, Imba and Marbel thermal springs. The conductive zones south and west of Mt. Zion are interpreted to be indications of possible minor outflows to the southwest towards the Bulatukan hot springs. The Kapatagan anomaly, delineated by previous SRT and VES data southeast of Mt. Apo, appears to be a signature of another outflow path to the southeast. In contrast, the MT data affirm previous interpretation about Tico anomaly located north of the study area being a shallow manifestation of relict alteration.