Inferring In-Situ and Immobile Water Saturations from Field Measurements

Abstract

This study developed models of vapor and liquid geothermal reservoirs, based on Darcy's law and material and energy conservation equations. These models can be used as tools to infer the in-situ and immobile water saturations from field measurements of cumulative mass production, discharge enthalpy and temperature. The knowledge of the in-situ and immobile water saturations is valuable in evaluating geothermal reservoir performance.

Knowing rock and fluid properties, and the difference between the stable initial, Tor and dryout, Td downhole temperatures, the in-situ and hmObif8 water saturations of vapor-dominated reservoirs can be estimated. On the other hand, the in-situ and immobile water saturation, and the change in mobile water content of liquiddominated reservoirs can be infened from the cumulative mass production, Am, and enthalpy, h', data. Comparison with two-phase radial flow simulation results confirmed the validity and usefulness of these models.