Utilization of Thermal-Mechanical-Hydrologic-Chemical Coupled Modeling to Investigate Fracture Network Permeability Evolution During Enhanced Geothermal System Stimulation at Desert Peak, Nevada

Affiliation(s)PIProject periodFunded by
DHS Reeves, Donald Matthew 08/01/2012 - 09/30/2013 University of Nevada, Reno

Project Description

Enhanced Geothermal Systems (EGS) techniques typically involve the stimulation of conventional and unconventional geothermal fields through the injection of high pressure fluid to enhance rock mass permeability through shear-dilation of existing fracture networks and/or the creation of artificial fracture networks through hydraulic fracturing. Permeability evolution in rock masses is controlled by the coupled influence of stress-driven thermal (T), hydrologic (H), mechanical (M), and chemical (C) processes, also known as THMC. A state-of-the-art, coupled THMC numerical framework, TFReact, is proposed to investigate pre- and post-stimulation permeability evolution at the Ormat Desert Peak, Nevada EGS experiment. Study results will further evaluate the effectiveness of EGS stimulation, identify contributions of specific processes to changes in fracture network permeability, and gain further insight into the life-cycle of an EGS project. This research is computationally and technologically innovative as THMC modeling approaches have only been applied to real EGS field tests in a few instances. Total project cost over a July 1, 2012 to June 30, 2012 time period is $69k with a 20% match provided from the Desert Research Institute. This funding will provide PI Reeves with 2 weeks of funding and 12 months of funding for a Ph.D. student, and will expand the capability and expertise of NSHE faculty and students into the relative new field of THMC modeling, with specific application to EGS. Project deliverables include two geothermal conference proceedings papers, a final summary report and supporting slides. This expertise will be leveraged in future proposals to DOE and other funding agencies.