Temporary Diverters for EGS Reservoir Optimization -- Field Applications

Abstract

Achieving multiple zone stimulation in an open-hole section of an EGS well could significantly reduce the cost of EGS power production by increasing flow capacity and production on a perwell basis. To prove this concept, a first operational step was taken in a geothermal field. The goal of the operation was to test the use of AltaRock Energy Inc. (AltaRock) proprietary diverters system1 in temporarily sealing off fractures in a geothermal reservoir and optimizing the injection/production profile of the given well. Success of the operation serves as a basis for multiple zone stimulation in EGS and conventional geothermal reservoirs. Multiple zone stimulation allows for greater production and substantial reduction in the cost of EGS power generation. GETEM modeling results for EGS show a reduction in the cost of power of up to 50 percent if three fracture zones can be successfully stimulated, versus the current method of single fracture set stimulation. Temporary diverters block flow to zones that are already stimulated or where stimulation is not desired. These proprietary diverter materials decay due to thermal degradation, producing environmentally benign decomposition products. Successful field results are presented along with a detailed explanation of the benefits of temporary diverters and how they could positively impact EGS projects and geothermal power production in general. These methods will be further validated at the upcoming Newberry Volcano EGS Demonstration. This work has been funded in part by DOE Grant DE-EE0002795, “Temporary Bridging Agents for Use in Drilling and Completion of Engineered Geothermal Systems.”