Critical parameters of the Jamin effect on the oil droplet passing through an abruptly constricted capillary tube laden with sodium dodecyl sulfate solutions.

This article focuses on investigating the Jamin effect—an additional resistance caused by morphological changes of droplets during two-phase flow in capillary tubes—and its critical parameters in sloped capillary tubes containing water and sodium dodecyl sulfate (SDS) solutions. Experimental and theoretical analyses reveal that oil droplets remain pinned at lower water velocities but depin and rupture at higher velocities, with the critical velocity increasing as the slope angle increases. The presence of SDS surfactants reduces interfacial tension, enabling oil droplets to pass smoothly through pore-throat structures without residual oil, and decreasing the time required for passage as SDS concentration rises and slope angle decreases. The study develops mechanical models to determine critical velocities and minimum applied pressure differences necessary to overcome the Jamin effect, providing insights relevant to enhancing oil recovery efficiency in petroleum engineering.