Abstract: The influence of rock deformation on reservoir porosity and permeability is taken into consideration in this paper. Based on WarrenRoot dualporosity model, the mathematical model of gas storage that accountes for fracture deformation′s influence is developed. A real case is calculated with the model. The result analysis shows that with the increase of the total operation time, gas storage pressure and gas injection well bottom hole pressure increases, porosity and permeability decrease. The gas storage pressure without deformation effect fluctuates in a certain range, and the bottomhole pressure of gas injection well without deformation effect basically remains the same. At the end of the 4th year within simulating time, gas storage pressure with deformation effect is 1.2MPa higher than that without deformation effect, gas injection well bottomhole pressure is 2.96MPa higher. While the porosity is 0.96 times of original value, and permeability is 0.87 times of original permeability, which indicates that the fracture deformation effect cannot be neglected in the study of depleted fractured reservoir underground gas storage. It is suggested that deformation effect should be take into account in field application and theoretical investigation of underground natural gas storage.

Key words: underground natural gas storage, fracture deformation, fracture porosity, fracture permeability, numerical simulation