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Data from: Reservoir in-situ stress state determined by retrieved granite cores from the Gonghe enhanced geothermal system and its implications, northeastern Tibetan Plateau, China

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Sep 19, 2024 version files 6.71 MB

Abstract

Enhanced geothermal systems (EGS) utilize hydraulic fracturing technology to create high permeability fracture networks in stress-anisotropy reservoirs. We recovered 16 granite cores from the Gonghe EGS, China, and estimated the stress state using the anelastic strain recovery (ASR) method. We show that the stress regimes in 1700–4000 m are strike-slip and thrust faulting, indicating that horizontal force dominates. The SHmax magnitudes of the reservoirs are not high, much lower than the Byerlee's limit domain ( =0.6–0.85). We infer that weak-friction minerals in fractures lead to this low-level critical stress state. The borehole failure indicators show that the SHmax orientations are NE35° 11°. The ongoing northeast expansion of the Tibetan Plateau is the first-order controlling factor for this stress state. Due to the proximity between Shmin and Sv, microseismic events during stimulation significantly migrate upwards. The focal mechanism of hydraulic-induced events provides direct evidence that our stress data is reliable.