Study On The Cover Stability Under The Condition Of Fluid Injection

At present,natural gas is more and more widely used in China.The construction of underground gas storage can supplement the shortage of natural gas storage capacity and ensure energy security.However,there is still no experience of building aquifer gas storage in China,which is still in the experimental stage.Based on the engineering background of a planned aquifer gas storage in North China,the numerical model of aquifer gas storage is established by using the large-scale finite element software ABAQUS.The effects on the deformation and stress of the reservoir and caprock under the condition of fluid injection is discussed,and the sensitivity of reservoir cap parameters to cap deformation and stress is discussed.(1)The fluid structure coupling numerical model of aquifer gas storage under two boundary conditions of closed boundary aquifer(Group A),semi closed boundary and open boundary aquifer(Group B)is established.The influence of fluid injection on the deformation and stress of reservoir and caprock under the two boundary conditions is analyzed.The results show that the influence of fluid injection on the deformation and stress of reservoir and caprock under the two boundary conditions is similar and different.(3)Based on A1 condition,the sensitivity of reservoir cap parameters to the deformation and stress changes of cap rock is discussed.It is concluded that the permeability coefficient of reservoir and caprock are sensitive to the deformation and stress change of caprock,while the influence of elastic modulus and Poisson's ratio of caprock on the deformation and stress change of caprock is not significant.The geostress coefficient has no effect on the deformation of caprock,but is very sensitive to the stress change of caprock.The number of load cycles also has a greater influence on the deformation and stress change of caprock.