Systems and techniques may be used to operate an enhanced geothermal system (EGS). An example technique may include applying a stimulation treatment including a proppant to generate a distributed network of fractures along wellbores between a horizontal geothermal injection well and a horizontal geothermal production well. The horizontal geothermal injection well and the horizontal geothermal production well may be positioned within a mixed metasedimentary and igneous formation.