Preliminary studies of the reservoir capacity and the generating potential of the Baca Geothermal Field, New Mexico

Abstract

A 50‐MW e geothermal power plant is being considered for the Baca site in the Valleys Caldera, New Mexico, as a joint venture of the Department of Energy (DOE) and Union Oil Company of California. To date, over 20 wells have been drilled on the prospect, and the data from these wells indicate the presence of a high‐temperature, liquid‐dominated reservoir. In this paper, data from the open literature on the physical characteristics of the field are used to estimate the amount of hot water in place (reservoir capacity) and the length of time the reservoir can supply steam for a 50‐MW e power plant (reservoir longevity). The reservoir capacity is estimated to be 10 12 kg of hot fluid by volumetric calculations using existing geological, geophysical, and well data. The criteria used are described and the sensitivity of the results discussed. The longevity of the field is studied using a two‐phase numerical simulator (SHAFT79). A number of cases are simulated based upon different boundary conditions and upon injection and production criteria. The results obtained from the simulation studies indicate that it is questionable that the Baca field can supply enough steam for a 50‐MW e power plant for 30 years. Although the estimated reservoir reserves greatly exceed those needed for a 50‐MW e power plant, the low transmissivity of the reservoir would cause localized boiling and rapid pressure decline during exploitation. It is therefore apparent that the conventional zero‐dimensional (lumped parameter models) cannot be used to evaluate the generating capacities of low‐permeability fields such as the Baca field.