FLUID STRATIGRAPHY OF THE COSO GEOTHERMAL RESERVOIR

A fluid model for the Coso geothermal reservoir is developed from Fluid Inclusion Stratigraphy (FIS) analyses. Fluid inclusion gas chemistry in well cuttings collected at 20 ft intervals is analyzed and plotted on well log diagrams. The working hypothesis is that select gaseous species and species ratios indicate areas of groundwater and reservoir fluid flow, fluid processes and reservoir seals. Boiling and condensate zones are distinguished. Models are created using cross-sections and fence diagrams. A thick condensate and boiling zone is indicated across the western portion of the field. The east flank area has a thinner condensate zone and thicker seal zone than the western portion. The boiling zones for both the western portion of the field and the east flank correspond to areas of increase permeability and present day production zones. Reservoir fluids are shown to rise to the north, which agrees with fluid inclusion studies. The boundary between the east and western sides of the field are evident in the cross-sections developed using this method