Stress sensitivity of tight reservoirs during pressure loading and unloading process

Nai CAO,Gang LEI

Fig. 6. Permeability retention rate under different β.The deformation degree parameter γ is influenced by the effective stress coefficient and rock particle radius. For different γ, the retention rate of rock permeability during the pressure unloading process was calculated by using the established model to analyze the effect of γ on permeability retention rate. The calculation result was compared with the permeability retention rate in the pressure loading process. As shown in Fig. 7, in the pressure unloading process, with the increase of γ, the damage extent of θ increases, which leads to an increase in the non-recoverable damage extent of the rock structural deformation, in other words, the stress sensitivity hysteresis increases.