Geothermal System Modeling of Roosevelt Hot Springs (RHS), Utah Using TOUGH2 Simulator

Abstract

Roosevelt Hot Springs (RHS) is a two-phase geothermal system located in the western side of Mineral Mountains, Utah. Previous study stated that the composition of the fluid has not changed since it was first produced in 1984, except for the effects of steam loss and injection fluid through well 14-2. To know the current condition of the geothermal system below the surface, conceptual model and reservoir simulation are made. The conceptual model is based on the results of geological, geophysical, and geochemical surveys that have been carried out in this area in previous studies. Furthermore, reservoir simulation using TOUGH2 is carried out by combining information of rock physical properties, initial conditions, boundary conditions, as well as sinks and sources to reach the natural state which is characterized by the similarity of the temperature to depth curve from the simulation results carried out with data from one exploration well and two monitoring wells. From the simulation results, it is known that the fractured granitoid reservoir is located at a shallow depth and is limited by the Opal Mound fault in the west which has low permeability. The heat source located in the eastern side of the RHS system, which is just below the Mineral Mountains, makes the fluid in the reservoir the hottest and has a temperature between 175-230°C.