Oil Recovery Improvements Based on Pickering Emulsions Stabilized by Cellulose Nanoparticles and Their Underlying Mechanisms: A Review.

The use of nanocellulose (NC)-based Pickering emulsions represents an advancement in chemically enhanced oil recovery (cEOR) methods. The main challenge of cEOR is to develop stable and efficient fluids for applications under reservoir conditions. Pickering emulsions have emerged as a possible solution for stabilizing chemical injection fluids. These emulsions are stabilized by solid particles instead of surfactants and have been the focus of research over the past decade because of their high stability. Although these emulsions present promising solutions, most research has focused on nonbiodegradable inorganic particles, raising concerns about their environmental impact. In this context, nanocellulose (NC) has emerged as an innovative and sustainable alternative due to its biodegradability, abundance, and unique surface chemistry. This contribution presents an exploratory literature review on the use of Pickering emulsions, focusing on nanocellulose in the context of enhanced oil recovery (EOR) as an alternative for fluid stabilization under reservoir conditions. The main mechanisms of oil recovery, such as interfacial tension reduction, in situ crude oil emulsification, capillary disjunction, pressure, and fluid rheological behavior, are discussed. This Review highlights the great potential of nanocellulose-based Pickering emulsions to make EOR processes more sustainable and emphasizes the need for further studies to understand the mechanisms involved. A total of 176 scientific articles were analyzed and evaluated to provide insights and contribute to the advancement of cEOR, in addition to addressing the challenges encountered.