Continuing Reinjection Returns in the Palinpinon Geothermal Production Field Negros Oriental, Philippines

Abstract

Reinjection (RI) returns continue to affect the Palinpinon field to date. Two recent cases were investigated using various geochemical techniques to illustrate this reservoir phenomenon.

In Palinpinon-?, the south west Puhagan wells displayed typical Rl return indicators, when PNSRD was utilized above its original acceptance of 60 kg's in the first quatter of year 2000. The RI well began accepting up to 760 kgls afier it was worked-over in June 7999. Themal and mass front breakthroughs were detected immediately from chemical and phys'ical measurements, and thus were mitigated immediately by reducing the Rl load in PNSRD to an optimal level of 70 kgKs or less.

In Palinpinon-2, condensate injection in SG3RD has resulted to returns, causing dilution of reservoir fluid in production well NJ3D. A mixing sumulation using the CHILLER soffware was made to demonsfrate the dilution process. No thermal decline was observed due to possible reheating of the returning condensate by the formation prior to mixing with the production reservoir.