ABSTRACT
Enhanced geothermal system (EGS) represents an advanced geothermal energy utilization technology whereas the idea itself is simple: for low-permeability rocks, a series of rock-fracturing procedures, such as hydraulic stimulation to create an artificially fractured reservoir, is performed. By circulating water through the stimulated region, heat can be continuously extracted from the rock, just like a natural hydrothermal system. EGS has drawn wide interest across the world. At least 31 EGS projects have been launched worldwide, but few of them are in real commercial operation. Significant financial risks are present for EGS projects, since the production potential of an EGS project is largely dependent on the quality of the fractures network in the EGS reservoir, which is a major challenge to effective control. Physically, the EGS subsurface geometry consists of multiple domains: injection and production wells, heat reservoir, and rock enclosing the heat reservoir.
