The Bacon-Manito Surface Thermal Features – Geochemical and Physical Changes After Three Decades (1983-2013) of Monitoring

Abstract

Surface thermal manifestations are important features of almost all geothermal fields in the world. During production stage, the effect of mass extraction and injection can be observed from these surface thermal features. The Bacon-Manito (BacMan) geothermal field, located in Albay, Philippines, is related to the Pocdol volcanic complex and has been of geothermal interest since exploration activities started as early as 1979. Power production, however, only started on 1993 when the first power plant, BacMan-1, was commissioned. The baseline physical and chemical characteristics of thermal areas in BacMan were compared with their characteristics after three decades of exploitation to determine the effects, if any, of continuous production. Results indicate that exploitation of the BacMan geothermal field did not have a significant effect on the chemical characteristics of the selected thermal springs, except for a single spring, which showed a continuous decrease in chloride. This indicates that this spring may have connection with the current resource. Physical characteristics of surface thermal features, such as water flow rate and surface temperature have remained generally unaffected, indicating pressure support and preserved high subsurface temperatures. The minimal effect on surface thermal manifestations in BacMan indicates that the current strategies implemented are capable of sustainable exploitation.