Experimental Study on Dynamic and Static Rock Mechanical Properties of Tight Sandstone Gas Reservoir

The comparative study of dynamic and static rock mechanical properties of tight sandstone is of great significance to deepen the understanding of deep tight gas sandstone geological structure and improve the efficiency of oil and gas development. In this paper, taking the tight gas sandstone of the Sulige Gas Field as an example, experimental research on the difference of dynamic and static elastic parameters under different temperature and pressure conditions was carried out. Furthermore, the mechanism causing the difference of dynamic and static elastic parameters under different measurement conditions is analyzed. The results show that the dynamic Young’s modulus measured under reservoir conditions is greater than the static Young’s modulus, and there is a good linear correlation between the dynamic and static Young’s modulus of rock samples. But the correlation between dynamic and static Poisson’s ratio is relatively poor. The existence of microfractures has great influence on the static deformation of rock. It is also found that the dynamic Poisson’s ratio of rock decreases with the increase of pressure and temperature. The longitudinal and transverse velocity changes of rock under reservoir conditions are the result of confining pressure and temperature combined in the experiment. In the process of dynamic splitting and crushing of sandstone, the strain rate increases with the increase of impact pressure. The rock has certain rebound effect during unloading. The stress time history curve of sandstone samples is related to the change of impact loading rate and the fracture failure mode. In addition, the accurate evaluation of rock mechanics parameters has a significant impact on fracture prediction.