ORGANIC SPECIES IN GEOTHERMAL WATERS IN LIGHT OF FLUID INCLUSION GAS ANALYSES
Conference Proceedings: ORGANIC SPECIES IN GEOTHERMAL WATERS IN LIGHT OF FLUID INCLUSION GAS ANALYSES
AbstractMeasurement of organic compounds in Karaha- Telaga Bodas and Coso fluid inclusions shows there are strong relationships between H2 concentrations and alkane/alkene ratios and benzene concentrations. Inclusion analyses that indicate H2 concentrations > 0.001 mol % typically have ethane > ethylene, propane > propylene, and butane > butylene. There are three end member fluid compositions: type 1 fluids in which alkane compounds predominate, type 2 fluids that have ethane and propylene and no ethylene and propane, and type 3 fluids that have propylene and butylene and no propane or butane. Alkane/alkene ratios increase regularly with depth in Karaha-Telaga Bodas anhydrite and quartz inclusions. Coso analyses show a similar change in benzene and alkane/alkene ratios with sample depth. Equilibrium calculations show that high-hydrogen fugacities and low temperatures favor alkane compounds, whereas high temperatures and low hydrogen fugacities favor alkene compounds. Benzene, propylene, butylene, and ethylene should form in that order as hydrogen fugacity decreases. The Coso and Karaha-Telaga Bodas analyses indicate that benzene concentrations and alkane/alkene ratios are directly related to hydrogen fugacity. The large differences in hydrogen fugacity are best explained by boiling, because hydrogen strongly partitions into the vapor phase and is thus stripped from the geothermal fluids. The change in alkane/alkene ratios downhole would be reversed if the reactions were temperature driven. Calculations explain why benzene is a common constituent of geothermal fluids. Methane will react to form benzene at relatively high hydrogen fugacities. The relationship between organic species and hydrogen suggests that equilibrium at Karaha-Telaga Bodas and at Coso is fluid dominated.
- Noman, D. I.; Moore and J.N.
- PROCEEDINGS, Twenty-Eighth Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, January 27-29, 2003, 1/1/2003
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Noman, D. I.; Moore, J.N.. 1/1/2003. ORGANIC SPECIES IN GEOTHERMAL WATERS IN LIGHT OF FLUID INCLUSION GAS ANALYSES. Proceedings of (!) ; (!) : PROCEEDINGS, Twenty-Eighth Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, January 27-29, 2003.