Bacon-Manito Geothermal Production Field: Reservoir Processes and Isotopic Changes after Twelve Years of Exploitation

Abstract

The response of Bacon-Manito Geothermal Production Field (BGPF) to about twelve years of exploitation is summarized by three reseruoir processes, namely: boiling, mixing and returns of injected brine. Mixing, characterized by dilution and migration of peripheral fluids, is dominant in the northern and central secfors of the field. Ihese comprise the Palayang Bayan and Cawayan secfors where there is evidence of migration of Masakrot fluids from the western part of the field and inflow of SO+-richa cid fluids from shallow zones. lndications of injection returns are a/so present in these two secfors. ln the Botong sector, the center of the upflow region, reseruoir boiling is experienced due to pressur e drawdown.

The deep reseruoir fluids are characterized by chemical and recent isotopic data from steam and water samples collected from rainfall and wells. lsotopic data confirmed the changes and geochemical processeso bseruedi n the reseruoir