Direct Numerical Simulation of Oil Displacement by Water within Porous Media UsingOpenFOAM: Effect of Wettability

Waterflooding (displacement of oil by water) is the mostcommon method to enhance the recovery from mature oilfields. Laboratory experiments have shown thatperformance of waterflooding in oil reservoirs issignificantly affected by wettability status (contact angle)of the porous media. The aim of the present study is todevelop a promising CFD model in OpenFOAM to beapplicable for pore scale simulation of two phase waterand oil in porous media. Using the developed model, theimpact of contact angle was investigated via micromodelscale simulation. The amount of residual oil saturation asa function of the contact angle is analyzed which is in linewith presented core experiments in the literature.The developed model is used to investigate the effectof wettability of the solid (rock) on the distribution,redistribution and displacement mechanisms in themodelled porous media. Results shed light on the physicsof displacement of oil by water within porous media. Forthe strongly water-wet condition the dominating oilentrapment mechanism is snap-off within water wettinglayers. For non-water-wet states the dominatingmechanism is oil bypassing due to the flow of non-wettingwater in larger pores. In addition to the amount, thedistribution of the residual oil was also affected by thewettability condition of the porous media. For the waterwetsystem the residual oil saturation was scattered in theporous media as small ganglia while for the non-water wetsystem the residual oil saturation is mostly continuous asextended ganglia within multiple pores.

Keywords:

Direct Numerical Simulation (DNS) , Computational Fluid Dynamics (CFD) , Contact Angle , Porous Media , OpemFOAM