Development of a reservoir stimulation model at Pilgrim Hot Springs, Alaska using TOUGH2

Abstract

This study has developed numerical simulations of the Pilgrim Hot Springs geothermal system, Alaska using the TOUGH2 software package for the purposes of assessing the resource potential for both direct use applications and electrical generation. This work has included the development of two simulation models, describing fluid and heat flow in the geothermal system, that were built using geological and geophysical constraints with model simulation parameters optimized via a history matching of subsurface temperature profiles. The reservoir simulation models were used to predict the heat loss from the system for both conductive and convective heat fluxes. These reservoir simulation models served as the basis for the development of reservoir stimulation models encompassing three production scenarios with various configurations of production and injection wells. These reservoir stimulation models were used to estimate the thermal energy from the production wells. The major significance of these stimulation models is that they help to determine the feasibility of development of the reservoir for production. The reservoir simulation models estimate about 26-28 MW thermal energy and the stimulation models estimate about 46-50 MW thermal energy for the Pilgrim Hot Springs geothermal system. These estimated values indicate a favorable resource when compared to other low temperature systems such as, Chena Hot Springs, Alaska; Wabuska, Nevada; Amedee, California; and Wineagle, California.