Abstract:According to the fluid flow characteristics in low-permeability porous media, a mathematical model is built, and the dimensionless permeability variation coefficient is used to describe the low-velocity non-Darcy flow. The variable permeability numerical simulation software is developed based on the black-oil model. Actual field data is used to simulate a five-spot well unit. The comparative analysis of Darcy flow, quasi-linear flow which assumes the starting pressure gradient to be constant and variable permeability flow, is carried out in the simulation. The oil production, water cut, oil saturation distribution and permeability distribution are compared, which indicates that the flow ability of the formation near the oil and water well is strong while the flow ability of the formation far away from the main stream line is weak; the formation flow ability becomes stronger with the decrease of the well spacing. When the fluid flows in low-permeability porous media, Darcy flow only occurs in area near the wells, and the variable permeability flow area is much larger than that of Darcy flow. The variable permeability numerical simulation results show the limitations of quasi-linear flow, which can not describe the change of liquid permeability with pressure gradient. The variable permeability flow plays a dominant role in fluid flow and the variable permeability numerical simulation software could be used to simulate the percolating process of the fluid in the low-permeability porous media quite accurately.