Fractures and faults are the main conduits for flow in enhanced geothermal systems (EGS). These fractures and faults may have spatial variations for which the aperture is not constant across the fracture plane. The presence of these spatial variations can result in flow channeling and reduced contact area and consequently could impact the thermal performance of the EGS. This study investigated the thermal performance of enhanced geothermal systems considering flow relative to the direction of fracture shear offset and considering spatial variations in the fracture aperture. The system studied consisted of a single fracture with a horizontal injector providing cold fluid, which contacts the hot rock of the EGS, and heat is extracted through a horizontal producer. Several aperture distributions were analyzed with the objective of determining if a direction of flow relative to the fracture shear offset provided better thermal performance. The results showed that where there is continuity across the fracture plane, the flow perpendicular to the fracture shear offset provided better thermal performance than flow parallel to the fracture shear offset. The thermal drawdown was inversely related to the average permeability across the fracture plane and the area contacted by the flowing fluid.

Press the Back button in your browser, or search again.

Copyright 2019, Stanford Geothermal Program: Readers who download papers from this site should honor the copyright of the original authors and may not copy or distribute the work further without the permission of the original publisher.