摘要：Current geostress evaluation using logging data can provide a basis for fracturing stimulation and optimization of horizontal well trajectories in tight sandstone reservoirs. In this paper, taking the upper Paleozoic coal measure tight sandstone reservoirs in the Ordos Basin of China as an example, the rock mechanics properties and geostress of tight sandstones were comprehensively evaluated. Firstly, the dynamic and static mechanical parameter conversion relationship was obtained according to the rock mechanics experiments. Then, the geostress was calculated by the hydraulic fracturing method. The calculation results showed that σ_H is mainly distributedin 24-70 MPa; σ_h ismainly distributed in 22- 43 MPa; and σ_v is mainly distributed in 34-55 MPa. The variation of the geostress in the longitudinal direction is very large, which is affected by the strong anisotropy of the formation. Geostress state of the target layer satisfies σ_h<σ_H<σ_v, however, some local geomechanical layers exhibit a high tectonic stress environment. The prediction of the minimum horizontal principal stress (σ_h) of tight sandstone was achieved by introducing the correction factor C* into the Newberry model. At the same time, considering the anisotropy of the geostress, a non-equilibrium structural factor (U_b) was introduced, and the maximum horizontal principal stress (σ_H）was predicted. The prediction results of the geostress have a well agreement with the measured results, which proves that the method is effective in predicting the geostress of strong anisotropic formation.
关键词：Tight sandstone formation;geo stress;rock mechanics;newberry model
