Abstract
<title>Abstract</title> <p>To generate maximum net electricity from hydraulic fracture-based enhanced geothermal systems over their lifetime, it is important to understand how the flow non-uniformity among fractures evolves with cooling of the rock to avoid early thermal breakthrough. Here, we use fully-coupled thermo-hydro-mechanical models to study the thermal decline and electricity generation capacity of these systems. We consider two cases: one with moderate initial flow non-uniformity and another with high initial flow non-uniformity due to the presence of a pre-existing fracture. The obtained results show that high circulation flow rates induce thermal breakthrough after several years as unequal cooling aggravates existing flow non-uniformity in the moderate case, disrupting electricity generation. We demonstrate that flow-control devices (FCDs), which restrict the entry of water into fractures through engineered perforations, can be effective in preventing thermal short circuiting. Activating FCDs when signs of thermal breakthrough are observed generates more cumulative net electricity than using them from the beginning of circulation for these cases. Yet, for cases with an initially large flow non-uniformity, using FCDs from the beginning of circulation can generate significantly higher cumulative net electricity. These findings establish a mechanistic framework for designing flow-control strategies that maximize long-term thermal sustainability and electricity generation.</p>