Aiming at spherical dual-porosity reservoir, an unsteady seepage model that based on the three different kinds of outer boundary (infinite, constant value and closed) conditions was established in this paper. Using the Laplace transform method, similar structure of dimensionless bottom pressure solution in the Laplace space and similar nuclear function were obtained. This is not only providing us a new road to further explore the inherent law of the solutions and compile corresponding analysis software, but also has a broad application prospects.

On the basis of percolation mechanism for dual-porosity, an effective wellbore radius model in the dual-porosity was established, and the Laplace space solution could be obtained by solving this model. The solution had a similar structure and could be simplified into a unified expression in the different outer boundary conditions. The solution with a similar structure can avoid the complex calculations, it is beneficial to analyze the influence of various parameters on the solution in the dual-porosity model, and facilitate to master and use by engineering technicians.