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ABSTRACT: Enhanced Geothermal Systems (EGS) is an emerging energy technology with increasing attention due to its potential to be developed in most places on Earth, helping to accomplish net zero carbon emissions. To comprehensively understand EGS complex environments and reach its commercial application, pilot demonstration projects, modeling, and laboratory tests are needed. Laboratory-scale tests can assess critical knowledge gaps by conducting research under controlled conditions, allowing to understand mechanisms and then extrapolate them at the field scale, especially those contributing to, and controlling, flow heterogeneity. Particularly, block samples are useful to study EGS because they enable the evaluation of interactions between wells, networks, and circulation schemes at reservoir conditions, especially heat/flow properties. Different practices can be performed at this scale regarding wells configuration. It is possible to create a fracture and then locate it aided by nondestructive evaluation methods and interpolations, after that, a production well can be drilled intercepting the fracture plane. Likewise, it is possible to drill the injector and producer wells at the beginning if fracture caging is intended. This under-stress experiment uses a large granite specimen of 30x30x45cm that was placed in a polyaxial frame to fracture and monitor fluid flow. To do this a fracture was created through hydraulic fracturing. Different multiphysics such as acoustic emission sensing and fiber optic cable, were used to monitor fracture creation and characterize fracture flow. 1 INTRODUCTION According to The Office of Energy Efficiency and Renewable Energy of the United States EERE (2022), geothermal resources have the confirmed ability to generate 90 GW of electricity by 2050, becoming a key component to face climate change. The main contributors to achieve this goal are Enhanced Geothermal Systems (EGS), unconventional reservoirs with significant stored thermal energy and low hydraulic connectivity i.e., Hot Dry Rocks, that can be found anywhere in the world. To unlock EGS potential, a certain number of challenges associated with reaching deep rock targets and creating large flow paths (fractures) in tight rocks, need to be solved (Villaquiran Vargas et al., 2023). In addition, a detrimental flow pattern such as flow channeling might occur in EGS, leading to premature cooling of the fractures that carry the fastest and largest volumes of fluid. By increasing the injection-production well spacing, the production life of a geothermal reservoir might be extended (Fu et al., 2015).
Villaquiran-Vargas et al. (Sun,) studied this question.