Analysis of fluid flow characteristics in spherical nonlinear seepage flow model for dual-porous reservoir with the elastic outer boundary

In order to truly describe the dynamic characteristics of bottom-hole pressure in the reservoir, in this paper, the elastic outer boundary condition is introduced to replace the three kinds of traditional outer boundary conditions (infinity, constant pressure, closed), and a spherical nonlinear seepage model is established for the dual-porosity reservoir, which takes into account wellbore storage, effective well diameter and quadratic gradient term. The solution of the model in the Laplace space is found, and the similar structural formula of the solution is obtained by combining the Laplace transformation with the similarity construction method. Subsequently, by the Stehfest numerical inversion method, the well test curve is drawn, and the influence of main reservoir parameters on bottom-hole pressure dynamics is analyzed. The introduction of the elastic outer boundary not only breaks the traditional fixed form of the ideal outer boundary condition, but also improves the interpretation accuracy of the reservoir boundary. At the same time, a more general representation of the model is put forward, which provides a more effective theoretical basis for further exploration of the seepage law of the reservoir. Simultaneously, the similarity construction method simplifies the complex calculation process of solving the model and provides a new idea for solving the more complicated percolation model of oil and gas reservoirs. The similar construction method simplifies the complicated calculation process of solving the model and provides a new idea for solving the more complicated percolation model of oil and gas reservoirs.