A Critical Review of Enhanced Oil Recovery by Imbibition: Theory and Practice

Imbibition is very common, occurring in life, material, chemistry, and energy. It plays an important role in enhanced oil recovery (EOR). The development of many reservoirs is beneficial to the imbibition process, such as fractured reservoirs, conventional reservoirs developed by a water-injection mode of huff-n-puff in their later development, and unconventional reservoirs with abundant micro–nanopores developed by the fracturing technology. Here, we present a critical review of EOR through imbibition. First, the mechanisms of EOR through imbibition are reviewed, including the mechanical analysis of imbibition in a capillary, imbibition models for rocks, and the scaling law. Then, the governing factors of EOR by imbibition are summarized, including the properties of rocks and fluids and the effects of the temperature and pressure. Besides, the EOR by imbibition in the oil and gas development is discussed, including the roles of surfactants, nanofluids, salinity, shut-in time, and injection/production rates. Finally, conclusions and outlooks are presented. This review provides systematic and recent insights about EOR by imbibition and a direction for future research on this topic, which can help for a better understanding of EOR by imbibition.