Numerical study on electrophoretic motion of charged droplets with implications for reducing emulsion droplet retention

Abstract

Emulsion flow in porous media has garnered significant attention for its potential to enhance oil recovery. While the Jamin effect can improve mobility during emulsion flooding, it can also lead to emulsion droplet retention. In this work, we investigate the potential of applying an electric field to modulate droplet flow and thereby achieve reduced emulsion droplet retention. The charged droplet's electrophoretic motion under an applied electric field is numerically simulated. This study analyzes the flow behavior of charged emulsion droplets as they traverse constricted microcapillary channels and porous media models. The results indicate that applying an electric field can reduce the flow resistance (expressed as the mobility factor) of emulsion droplets in the constricted channel from 1.458 to 1.349. In addition, when encountering obstruction, the droplets exhibit varying regimes (passing or breaking) that are influenced by their size and the associated electrical capillary number. Remarkably, it was found that an electric field reduces droplet retention in porous media in two distinct ways: (i) assisting droplets through the throat under small electrical capillary numbers; and (ii) forcing the droplet to breakup under high electrical capillary numbers. Furthermore, the permeability of the porous medium increases from 2.31 Darcy at CaE = 0 to 3.42 Darcy at CaE = 233.96 due to the reduced retention of droplets. These findings provide valuable insights into the role of emulsion droplet electrophoresis in improving permeability and reducing droplet entrapment.