Research of Reservoir Property Stress Sensibility of Abnormal High Pressure Gas Reservoir

Key words: 
• abnormal high pressure /
• reservoir /
• stress sensibility /
• volumetric strain

Abstract: In the develop ing of abnormal high p ressure gas reservoir, the stress of reservoir rock will be changed by out-flow of the gas, and the rock will have elastop lastic deformation, on the contrary, the deformation influence porosity and permeability of reservoir. Therefore, it has important significance to study the porosity and permeability stress sensibility. This paper presents the reservoir stress sensibility model in theory based on the theory of rock mechanics and brings forward a buckling equation then takes it as a method to evaluate reservoir stress sensibility. This paper put theory and experiment rule together, prove the theory to be true by the experiment of reservoir stress sensibility under the simulating formation situation. The relational exp ressions between the porosity and the permeability of reservoir rock and the reservoir pressure are derived based on the theory of rock mechanics and the theory of seepage flow in porous media. And the sensibility of actual cores to the simulated formation stress is studied in laboratory. The varying laws of the porosity and the permeability of reservoir rock with confined pressure are obtained. The effect of the stress sensibility of reservoir on the development of gas reservoir is also discussed. The deformation of abnormal high pressure reservoir rock decreases the porosity and permeability of reservoir, Changes the seepage flowing ability of the reservoir, and increases the elastic energy of gas-bearing reservoir. Therefore, in the development process of the deformable gas reservoirs, the maintenance of the original pressure inside the gas reservoir is important to getting and maintaining high oytput and lasting the production time of the gas reservoir