A Capillary Pressure Model for Geothermal Reservoirs

Abstract Steam-water capillary pressure is often either ignored or determined artificially in geothermal reservoir engineering. However steam-water capillary pressure plays an important role in geothermal reservoir performance and may not be substituted by air-water capillary pressure. To this end, preliminary mathematical models have been developed to calculate drainage and imbibition steam-water capillary pressure respectively. Using these models, steam-water capillary pressure in geothermal reservoirs can be computed once porosity, permeability, and reservoir temperature are known. Experimental data of steam-water capillary pressure measured in Berea sandstone and inferred from adsorption tests in the rock from The Geysers were compared and used to develop the steam-water capillary pressure models in both drainage and imbibition cases.