Understanding In Situ Stress Complexities in EGS Reservoirs through True-Triaxial Block Fracturing Experiments on High Temperature Analogue Utah FORGE Granites

Understanding and estimating in-situ stresses in Enhanced Geothermal Systems (EGS) present significant challenges due to the intricate nature of EGS reservoirs and various influencing factors such as deviating wellbore directions, strong thermal stress field coupling, and the anisotropy and heterogeneity of granite properties. This study highlights the importance of considering these complexities for a more accurate in-situ stress estimation, and it also underscores the limitations and potential ambiguities associated with traditional methods of inferring in-situ stress from hydraulic fracturing stress tests. To address these challenges, we introduce a series of high-fidelity experimental apparatuses for true-triaxial block fracturing experiments on high-temperature analogue Utah FORGE granites, maintaining geometric similarity to effectively replicate field scenarios. Through a series of preliminary experimental runs, we demonstrate that our experimental setup can effectively explore how thermal effects, well deviation angles, material anisotropy, and operational choices impact pressure responses and fracture trajectories. Moreover, the key components of in-situ stress estimation can be extracted and validated through our experiment, providing a solid foundation for either validating existing in-situ stress estimation theories or proposing new ones., We also set the stage for developing a comprehensive hydraulic fracture patterns database, which will enable further integration of computer vision techniques with traditional experimental fracture observation methods. This approach aims to deepen our understanding of the complexities in EGS reservoirs and pave the way for future data-driven investigations.