Objectives The magnitude and direction of in−situ stress are important parameters for well placement, fracturing design and reservoir evaluation in hot dry rock development. It is of great significance to study reservoir stress state for hot dry rock development.

Methods In this paper, the characteristics of current stress field in Gonghe Basin are analyzed based on regional geological structure evolution, focal mechanism solution and inversion results, statistics of joints and fissures, and in−situ stress measured data. Combined with the reservoir structure and stratigraphic lithofacies characteristics of Gonghe GR2 well, a three−dimensional model is established, and the three−dimensional in−situ stress data of well GR2 in Gonghe Basin is obtained through numerical simulation by using orthogonal anisotropic elastic constitutive relation. The regional tectonic stress field and occurrence conditions of dry hot rock resources are discussed.

Results The results show that: ① The simulated stress distribution is consistent with the theoretical value, which meets the requirements of initial displacement accuracy, and finally predicts the distribution characteristics of in−situ stress field in the well. ② In the depth range of 500~4500 m, the relationship of three principal stresses is principal stress is σ_v> σ_H >σ_h, indicating that the stress structure in this region is favorable to normal fault activity. ③ The maximum horizontal principal stress direction of Gonghe Basin in Qinghai province is mainly NE direction compression deformation, which is conducive to low fluid permeability and low heat transfer of granite. ④Under the action of a unified regional stress field, the faults may be come instability near the injecting well, when the continuous injection pressure on the ground reaches or exceeds about 19.9 MPa during the water injection development of 3900~4500 m depth in the study area, leading to the occurrence of medium and small earthquakes, which should be prevented in the development and utilization of the hot dry rock.

Conclusions This study have certain reference value for geodynamics research and the safe development and utilization of dry hot rock in Gonghe Basin.