Study on relative permeability characteristics affected by displacement pressure gradient: Experimental study and numerical simulation

• Effect of DPG on oil–water relative permeability was examined using experiments.
• Empirical correction of oil–water relative permeability considering DPG effect was proposed.
• Numerical simulation integrating DPG effect on relative permeability was established.
• Effect of relative permeability change due to DPG on reservoir performance was discussed.

The relative permeability is a key parameter for describing multiphase flow in porous media. In this paper, a series of experiments were conducted to study the impact of displacement pressure gradient (DPG) to relative permeability curves using five cores from Shengli Oilfield. Then, an empirical model was proposed to consider the impact of DPG. Finally, the numerical simulation model was established by introducing empirical correction formula into the traditional black oil model, and the effect of DPG on reservoir performance was analyzed. Result shows that with the increase of the DPG (in a range of 0.125–0.498 MPa/m), the residual oil saturation decreases, the cross point of water and oil relative permeability curves moves to the right, and the relative permeability for water phase increases under the same water saturation. In the type III relative permeability curve, with the decrease of DPG, the water relative permeability decrease and the oil relative permeability keeps the same. With considering correction of relative permeability will improve the recovery factor and simulation accuracy.