Similar Structure of Solution for the Model of Nonlinear Spherical Seepage in Composite Reservoir

The well testing model of nonlinear spherical percolation problems for composite reservoir is established under three different outer boundary conditions: closed boundary,constast pressure boundary,infinity boundary. the mathematical model are linearized by using variable substitution method, and then its solutions are derived by Laplace transform. According to the theory of similar structure of solutions to the differential equations, we obtain the similar structure of the solutions .The theory of similar structure is beneficial to understand the inherent laws of solutions and analyze the influence of parameters to solutions.