Analysis of bottom hole pressure of unsteady flow in dual-medium fracturing vertical well

Abstract In order to improve the validity of bottom hole pressure model, and simplify its calculation process, a mathematical model instantaneous for unsteady flow was established by considering crossflow between fractures matrix. Different conditions, including reservoir top has constant pressure, were considered. The basis obtaining is solve diffusivity equation with integration axisymmetric transformation similar methods, which presented first time. from traditional method using Green’s function source solution, this paper uses Laplace transformation, separation variables obtain analytical solution domain. Then, Stephenson Numerical used numerical in real results agree simulations actual test data, suggesting accuracy method. Finally, sensitivity analysis revealed that curve can be divided into eight stages, namely, early linear flow, continuous transition section, fracture formation crossflow, transitional pseudo-radial boundary control flow. advantage utilized incorporate exchange coefficient skin factor efficiently, providing theoretical optimizing production difference determining reasonable productivity.