A Universal Model of Stress Sensitive Coefficient in Low Permeability Reservoir

To describe the stress sensitivity of low permeability more accurately, the permeability changes were measured by variable fluid pressure method. A stress sensitive coefficient was presented according to the definition method of rock compressibility, and a universal model of stress sensitive coefficient was built taking into account of the effect of pore structure, effective stress and hysteresis effect. The results show that permeability decreases in step shape with the increase of effective stress, and it is relative to pore structure and stress loading way. The stress sensitive coefficient can characterize the rock sensitivity quantitatively. The universal model reflects the effect of both the internal factor and external factors, so it has a wide adaptability.