Applications of gas chemistry in evaluating physical processes in the Southern Negros (Palinpinon) geothermal field, Philippines
- CNR-International Inst. for Geothermal Research, Pisa (Italy)
- PNOC-Energy Development Corp., Fort Bonifacio (Philippines). Geothermal Div.
Three major physical processes have occurred in the Palinpinon geothermal system due to exploitation from 1985 to 1991. They were identified using gas compositions and equilibria involving H{sub 2}, H{sub 2}S, CH{sub 4} and CO{sub 2} to calculate temperature and vapor fraction in the reservoir. The first process is pressure drawdown in the southern part of the field, producing a local increase in the vapor fraction, with the liquid maintaining a high measured temperature, close to 300 C. The second process is vapor loss from an original liquid phase during its ascent through fractures. Wells affected by this process show high degrees of vapor loss (> 10%) when evaluated at the original high temperature of the liquid (290--300 C). But if vapor loss is modeled to occur at much lower temperatures (220--250 C), more realistic vapor losses (1--3%) are calculated. The last process involves mixing and cooling due to injection fluid returns to wells located in the northeastern part of the field. For some wells the fraction of injected brine in total temperatures can decline from 290 to 300 C to as low as 215--220 C, corresponding to periods when most of the produced fluids are derived from injected brine. Gas geothermometry gives a more reliable temperature estimate than quartz geothermometry for fluids with high fractions of injected brine, as the gas equilibria reflects the local reservoir temperature.
- OSTI ID:
- 143824
- Journal Information:
- Geothermics, Vol. 22, Issue 5-6; Other Information: PBD: Oct-Dec 1993
- Country of Publication:
- United States
- Language:
- English
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