Evaluation of the Stress-Sensitivity for Permeability in Zhenjing Low-Permeability Sandstone Rock

This paper discusses the stress-sensitivity evaluation of low-permeability sandstone with the completion of the laboratory study on the stress-sensitivity for permeability of Zhenjing low-permeability oil reservoir. The experiments included two cycles,with each running at constant-confining-stress by increasing and decreasing pore pressure. The results of experiment study and stress-sensitivity evaluation indicate that at initial reservoir pressure,depletion type of development exerts no effect on the reservoir permeability,but flood development can improve the permeability to some degree. Meanwhile the study of the equation of effective stress law shows that the effective stress coefficient obtained for the permeability is constant and very small. This may explain the fact that the permeability of Zhenjing oil field is non-sensitive to the stress from mechanism.