Abstract:Kela 2 gas reservoir is the largest dry gas reservoir so far discovered in China. It has such features as high pressure and pressure coefficient,and gas reservoirs with a pressure coefficient of over 2.0 are not commonly found. The abnormal high-pressure gas reservoirs are quite different in characteristics and performance during the process of depletion exploitation. During the depletion exploitation,the formation pressure depletes slowly;but the effective stress to the rock grain increases. The effective stress may cause rock to deform,resulting in the elastic or plastic deformation;and this deformation makes the rock physical property parameters such as porosity and permeability become quite sensitive to effective stress. Therefore,it is necessary to know the property of stress sensitivity for this abnormal high-pressure reservoir. The testing chart and method being used to study the property of stress sensitivity are designed. By means of testing porosity and permeability of sand rock core sample of Kela 2 gas reservoir under different effective stresses,the reduction property of porosity and permeability is obtained. The results demonstrate that the rock permeability behaves in an exponential manner with the effective stress variation,and the lower initial permeability would lead to the stronger stress sensibility;the same variation has been found for the porosity,but the magnitude of the effective stress sensibility of porosity is lower than that for permeability. The complete stress-strain curve is obtained through triaxial high temperature and high pressure rock deformation- seepage test. The characteristic of permanence plastic deformation with the dropping of the formation pressure can be quantitatively described;this is the reason of the stress sensibility of reservoir physical property. These results offer a very important base and guide for researching and designing the production performance of an abnormal high-pressure gas reservoir.