Numerical Model Studies of Enhanced Geothermal Systems

Enhanced Geothermal Systems (EGS) are being developed around the world as a method of extraction of thermal energy. A good EGS reservoir should maintain a small thermal drawdown and low water loss. All factors must be considered for optimal levels of energy production and assuring a long life span of the reservoir. It is where numerical simulation models are used as reservoir performance predictive tools to find these parameters.;A benchmark problem for the Fenton Hill Phase I EGS was numerically simulated as the first task with four runs contemplating a single planar penny shape fracture in the rockmass with a given lateral extension. The first run evaluates a constant aperture fracture while the second run deals with a variable aperture, penny shape fracture. The third and fourth runs evaluate a similar model but with an increased backpressure in the reservoir.;The second task is a challenge problem with multiple fractures in Fenton Hill Phase II. The geometry of the fractures had to be determined from the literature data that included dip, strike and depth information. MicroEarthQuakes (MEQ) data were also available from field measurements at Fenton Hill Phase II for graphical matching the fracture positions in the model in 3D AutoCAD. The fluid circulation was modeled assuming planar flow channels and using fine spatial discretization in the fracture volumes. Hydro-Mechanical processes are matched with experimental flow measurements data. Calibration was achieved by matching between the model prediction and the steady state injection flow test experiment at Fenton Hill Phase II.