Nonlinear Problems of Low-Velocity Non-Darcy Seepage Flow

The pores of low-permeability oil and gas reservoirs are small, with low porosity and permeability. The interaction between the fluid and the pore wall is strong, and the fluid flow in the reservoir has a threshold pressure gradient. Only when the reservoir pressure gradient exceeds the threshold pressure gradient can the fluid flow, as shown in Fig. 4.1. In addition, the crude oil seepage flow in heavy oil reservoirs also has a threshold pressure gradient, due to the non-Newtonian Bingham fluid characteristics of high-viscosity heavy oil, the fluid needs to overcome the yield stress τ to flow. Therefore, the oil seepage flow in low-permeability reservoirs and the crude oil seepage flow in heavy oil reservoirs both belong to the category of low-velocity non-Darcy seepage flow and no longer follow Darcy’s law.