ESPCI web site
Complex fluid flows and interface dynamics in microfluidic systems
Aurélien Duboin, doctorant - PhD student Crédits : ESPCI ParisTechTo better understand enhanced oil recovery processes, we performed immiscible biphasic flows in microfluidic geometries, involving oil phases and aqueous phases. We study the effect of the addition of polymers in the aqueous phase on the water/oil interface dynamics.
We work first in a common microfluidic flow-focusing geometry, implying elongational flows, with a semi dilute polymer solution as the outer phase and a Newtonian oil as the inner phase. We observe new interface regimes linked to the non-Newtonian behavior of the outer phase. The elongational properties of the polymer solution favour the formation of cusps and micrometric jets, and the normal stresses that arise in the polymer solution, contribute to stabilize the jet over large distances which allow us to produce microfibers in the system.
_Besides, we use geometries simulating the typical configuration of a reservoir in oil industry, so as to study, in a systematic way, the effects of polymer solutions (viscosity/elasticity) on the oil phase driving, at pore and network scales. We characterize the influence of the viscosity ratio, the capillary number and wetting conditions, on the global pattern in the network and on the oil recovery rate.
Lastly, we implement a dry-phase surface treatment method to improve the hydrophilicity of a material compatible with crude oil flows, and succeed in making microsystems with controlled and patterned wettability, down to the micrometric scale.
Aurélien Duboin PhD student at the MMN laboratory