Changes in Plant Inlet Gas Chemistry with Reservoir Condition, Location, and Time Over 15 Years of Production at the Geysers, CA

Abstract

Pacific Gas Electric Co., the largest generator of electricity from Geysers steam, has measured concentrations of carbon dioxide hydrogen sulfide methane (CH,), ammonia (NH,), hydrogen nitrogen oxygen and total noncondensible gas in steam delivered to each operating power plant on a monthly basis for approximately 15 years. These data represent weighted average steam compositions for portions of the wellfield that provide steam to a given power plant. A comprehensive database was compiled and reviewed for selected power plants (Units 11, 12, 14, and 18). Gas chemistry indicates: temporal increases in increases relative to H, in dry gas with time and with increasing and mass flow of increases with time in all units. Additionally, temporal trends in gas chemistry vary by location of individual units. Lateral trends in initial noncondensible gas chemistry between units located from the southeastern Geysers (low to the northwest Geysers (high and temporal trends at individual units are consistent with a source of noncondensible gas external to The Geysers. original steam source.