Dynamic contact angle effect on water-oil imbibition in tight oil reservoirs

Imbibition is one of the best methods for developing tight oil reservoirs. However, the dynamic contact angle (DCA) on imbibition is still unclear and limits the enhanced oil recovery of tight reservoirs. Here, the DCA effect is successfully coupled with two-phase seepage formulas, and a model of the DCA effect on imbibition for tight reservoirs is proposed. The results showed that: the influence of DCA on imbibition recovery with time has four stages (first increasing, then decreasing, then stabilizing, and finally decreasing). The DCA effect reduces the imbibition velocity of the first stage, but increases the imbibition velocity of the second stage. The AFO, TEC, TEO, and OEO boundaries have the same recovery enhancement rate of −27.7% at 26 s. The DCA effect on imbibition is proportional to the friction of a contact line, viscosities and interfacial tension, and wettabilities, while it is inversely proportional to an imbibition area. With a decreasing permeability or pore radius from 200.0 to 28.3 nm, the DCA effect on recovery first decreases from 44% to 38% and then increases to 41%. This work revealed the DCA effect on imbibition and provided insight into the enhanced recovery of tight reservoirs by imbibition. •An imbibition model considering the DCA effect is established.•The DCA effect is successfully coupled with two-phase seepage formulas.•The DCA effect on imbibition recovery with time has four stages.•Four boundaries have the same recovery enhancement rate at 26 s.