East Mesa -- Geology, Reservoir Properties and an Approach to Reserve Determination

The East Mesa KGRA is located in an area of anomalously high heat flow on the east flank of the Salton Trough, at the southeast corner of the Imperial Valley of California (see Fig. 1). Ten producing wells have been drilled within the East Mesa KGRA, including three by Republic Geothermal in the northern portion, five by the U.S Bureau of Reclamation in the central area, and two by Magma Power Co. to the south (see Fig. 2). The intent of this presentation is primarily to illustrate an approach to reserve determination applicable to Republic’s lease area. The approach is analogous to a volumetric calculation for determination of conventional oil and gas reserves. First, the total initial heat content (enthalpy) of the reservoir was calculated between a bottom of 9000 feet and a top defined by the 300ºF surface. Second, an estimate was made of the portion of this initial heat content that can be expected to be recovered during the economic producing life of the area by using reservoir simulation studies of a single five-spot reinjection pattern. Lastly, a conversion efficiency was developed that relates the heat content of the produced water to the electrical energy output. 11 refs., 9 figs., 7 tabs