| Waterflooding has been widely adopted to enhance the recovery of oil from reservoirs beyond what is possible from primary recovery. Specifically, low salinity waterflooding (LSW) was developed and successfully applied to the oil production process, demonstrating higher recovery efficiency than conventional waterflooding, yet the underlying mechanism remains controversial. A comprehensive knowledge of oil/brine/rock interactions is necessary to completely unravel the mechanism of the low salinity effect (LSE). We report upon the development of a microfluidic device for multiphase interfacial testing with length scales comparable to the pore sizes of oil reservoir rock. Unlike in conventional core flooding tests, however, fluid-fluid phenomena can be easily visualized within microfluidic devices under a microscope. Oil snap-off, a ubiquitous phenomenon occurring when crude oil flows through water saturated porous media in the reservoir, can be controlled within a microfluidic flow-focusing geometry. The size of generated droplets is interpreted as a measure of interfacial stability, or the resistance to snap-off. This device was used to probe the influence of factors like brine salinity, brine composition and asphaltene content upon crude oil-brine interfacial properties. To better simulate reservoir pore topology, glass microfluidic devices with triangular channels have been introduced as a superior surrogate of porous media in the reservoir. Studies were performed on the interactions among crude oil/brine/rock. Ultimately, by integrating the studies of interfacial properties of crude oil-brine and waterflooding simulations, a better insight on the LSE will be achieved. |
