Multiphase fluid flow dynamics dominate processes used to recover the majority of hydrocarbon resources produced by global energy industries. Micromodels have long been used to recapitulate geometric features of these processes, allowing for the phenomenological validation of multiphase porous media transport models. Notably, these platform surrogates typically preserve the complexity of reservoir conditions, preventing the elucidation of underlying physical mechanisms that govern bulk phenomena. Here, we introduce a microfluidic flow focusing platform that allows crude oil to be aged against brines of distinct composition in order to evaluate the pore-level effects of chemically-mediated interfacial properties upon snap-off. Snap-off is a fundamental multiphase flow process that has been shown to be a function of aqueous phase chemistry, which in turn establishes the limits of crude oil recovery during enhanced oil recovery operations. Specifically, this platform was used to evaluate the hypothesis that low salinity brines suppress crude oil snap-off, thus enhancing recovery. This hypothesis was validated and conditions that promote the effect were shown to, unexpectedly, develop over a matter of minutes on the pore scale. Microfluidic snap-off experiments were complemented by finite element fluid dynamics modeling, and further validated against a classical instability framework.