We evaluate stress state in the northeastern Tibetan Plateau (Gonghe EGS) using anelastic strain recovery (ASR), wellbore breakouts, and moment tensor (MT) solutions. All methods confirm that the stress regime at ~1700–4000 m is strike-slip transitioning to thrust faulting and aligned with tectonic compression (NE-SW). S_Hmax magnitudes in the critically stressed reservoir are much lower than Byerlee's limit (μ=0.6–0.85) and attributed to frictionally weak chlorite infill on fractures in a critically stressed crust. Borehole breakouts confirm that S_Hmax is orientated N35°±11°E - congruent with the ongoing northeast expansion of the Tibetan Plateau and representing the first-order control on stress state. Microearthquakes generated during fluid-injection stimulation of the Gonghe EGS reservoir migrate upward, confirming the proximity of the minor principal stresses S_hmin and Sv and providing further direct evidence of the fidelity of the stress estimates.

 

Stress state; Anelastic strain recovery; Borehole damage; Fluid-injection-MT Solutions; Enhanced geothermal systems; Gonghe Basin