Pore-scale Imaging of Oil-brine Movement During Waterflooding with Wettability Alteration from Tight Sandstone

To clarify the impact of salinity waterflooding on oil displacement efficiency and the microscopic mechanism, we have used micro-CT, nuclear magnetic resonance, high-pressure mercury injection, and other means to conduct an experimental analysis of salinity waterflooding. The results show that imbibition has little contribution to oil displacement efficiency, and the change in wettability is the main microscopic mechanism of low salinity waterflooding. However, the presence of corner flow can lead to a large amount of dropwise residual oil distribution, affecting the waterflooding effect, and seriously restricting oil recovery. When a strong hydrophilic phenomenon existed, pore size is no longer a key control factor for oil displacement efficiency. This study provides a theoretical reference for the influencing factors of different displacement methods on oil displacement efficiency.