The B6 metamorphic buried hill condensate gas reservoir exhibits a highly compact matrix, leading to a rapid decline in bottom-hole pressure during initial production. The minimal difference between formation and saturation pressures results in severe retrograde condensation, with multiphase flow further increasing resistance. Conventional numerical simulations often overestimate reservoir energy supply due to their failure to account for this additional resistance, leading to inaccuracies in bottom-hole pressure predictions and gas–oil ratio during history matching. To address these challenges, this study conducted research on nonlinear numerical simulation for buried hill condensate gas reservoirs and established a method for calculating a multiphase pressure sweep range based on the well testing theory. By correcting and fitting the pressure propagation boundaries with numerical simulation, the nonlinear flow parameters applicable to the B6 gas field were inversed. This study revealed that conventional Darcy flow is inadequate for predicting pressure propagation boundaries and that it is possible to reasonably characterize the pressure sweep range through nonlinear flow. This approach resulted in an improvement in the accuracy of historical matching for bottom-hole pressure and gas–oil ratio, which improve the historical fitting accuracy to 85%, providing valuable insights for the development of similar reservoirs.

Fractured reservoirs have developed fractures, strong heterogeneity, and complex seepage patterns. The analysis of core and imaging logging data in Bohai BZ Oilfield shows that there are a large number of fractures developed in the formation, with some wells having up to 6-8 fractures per meter. To study the impact of fractures on seepage, a multi fracture system seepage field simulation method was established, and the characteristic curves of flow lines under different fracture shapes were drawn. The fracture flow line morphology shows that there is a significant difference in the distribution of flow lines between the presence and absence of fractures, and the location of the fractures The size and shape of the reservoir have varying degrees of influence on the distribution of the streamline. The streamline around the well is distributed radially around it. When the fluid encounters an area with developed fractures, it first flows into the fractures and then flows from the fractures towards the wellbore. At the same time, based on the characteristics of fracture development in BZ oilfield and the theory of vertical fracture well testing, a dual medium multi fracture system oil well testing model was established. The model was numerically solved using Laplace transform, and a dual logarithmic curve chart for dual pore medium multi branch fracture well testing was obtained. The effects of fracture branching number, fracture length, conductivity coefficient ratio, and fracture conductivity on the shape of the testing curve were analyzed. The established well testing interpretation model can analyze oilfield stratigraphic information, reservoir fracture development, and boundary conditions. The research results have important guiding significance for evaluating the dynamic performance of oil wells in a dual pore medium multi fracture system and designing oilfield development plans.