Fracture Sustainability in Enhanced Geothermal Systems: Experimental and Modeling Constraints

Abstract Enhanced geothermal systems (EGS) offer the potential for a much larger energy source than conventional hydrothermal systems. Hot, low-permeability rocks are prevalent at depth around world, but challenge of extracting thermal depends on ability to create and sustain open fracture networks. Laboratory experiments were conducted using suite selected rock cores (granite, metasediment, rhyolite ash-flow tuff, silicified rhyolitic tuff) relevant pressures (uniaxial loading up 20.7 MPa fluid 10.3 MPa) temperatures (150–250 °C) evaluate impacts circulating fluids through fractured by monitoring changes in aperture, mineralogy, permeability, chemistry. Because disequilibrium with (deionized water) was used these experiments, there net dissolution sample: this increased increasing temperature experiment duration. Thermal-hydrological-mechanical-chemical (THMC) modeling simulations performed tuff test predict observed changes. These two steps: thermal-hydrological-mechanical (THM) simulation effects compression fracture, thermal-hydrological-chemical (THC) reactions porosity, permeability. point out how differences chemistry, geomechanical properties influence long asperity-propped apertures may be sustained. Such core-scale can EGS reservoir behavior field scale.