Enthalpy Trends as Indicator of Reservoir Processes in Palinpinon-1 Southern Negros Geothermal Production Field, Philippines

Abstract

Continuous exploitation in the Palinpinon- 1 sector of the Southern Negros Geothermal Production Field resulted to major changes in the reservoir. fhese changes have been diligently monitored using standard geochemical parameters such as reservoir chloride (Clres), total discharge COP (COztd), and TSiO2. A supplementary method, the enthalpy method, has been forwarded as a reservoir process monitohg technique. Assessment of the said method in the Palinpinon-1 sector of the Southern Negros Geothermal Roduction Field reveals that the enthalpy method complements the standard geochemical monitoring techniques in indicating the different processes occurring in the reservoir. Three major reservoir processes have been identified. The first is reinjection breakthrough brought about by the close proximity and direct fault connections between the production and reinjection wells. Recovery from reinjection returns was deteded in some wells alter implementation of mitigating measures such as the transfer of the reinjection sink to a farther location. The second process is boiling induced by pressure drawdown that eventually cgused production in the upper two-phase an steam zone in some wells. Lastly, entry of 8old acid fluid also occurred possibly as an effect of the decline in reservoir pressure.