Velocity effects in emulsion flow through porous media

Abstract

Velocity plays an important role in the flow behavior of dispersed drops in underground media. Its magnitude designates whether a drop is captured, breaks up, or percolates through the medium. A quantitative description of these effects is lacking. This work investigates the possible roles of velocity in the transport of dilute, stable oil-in-water emulsions through underground porous media from the viewpoint of deep-bed filtration. A wide range of capillary number is considered. Theoretical analyses are presented for droplets having sizes corresponding to the two capture regimes of straining and interception. For the straining capture regime, the effect of velocity is important when capillary number is on the order of 10 −4 or above. For the interception capture regime, velocity effects are important when capture is in the secondary-minimum energy well and the velocity is close to a critical re-entrainment value. In both capture regimes drop breakup occurs only when the capillary number is about unity. The theoretical findings are verified by new experimental studies on the flow of oil-in-water emulsions at velocities of 0.005 to 0.08 cm/s in sandpacks with permeabilities of 0.7 and 2 μm 2.