Capillary-driven mobility control in macro emulsion flow in porous media

► Experimental evidence of water mobility control by capillary driven mechanism. ► Existence of a critical capillary number below which mobility drops significantly. ► Estimation of critical capillary number from viscous to capillary pressure ratio. ► Evidence of efficient liquid–liquid displacement at low enough capillary number. ► Use of this capillary driven mobility control mechanism as EOR method. We show that the mobility of an emulsion with drops larger than the porous throats is a strong function of the local capillary number; it falls as the interfacial forces become stronger (low capillary number). Emulsion drops have little effect on the fluid mobility at high capillary number. This flow behavior can be used as a selective mobility control mechanism driven by capillary forces. The flow rate and emulsion characteristics can be selected in such a way that fluid mobility near the injecting source remains high, allowing the emulsion to reach the location where the mobility control is needed. To prove the benefit of capillary-driven mobility control, we study the displacement of mineral oil by water and emulsion at two capillary numbers by measuring the volume of displaced fluid. Higher efficiency displacement due to high mobility of the displacing fluid only occurs at low capillary number.