Study on the Mechanism of Nanomaterials in Improving Oil Recovery in Unconventional Reservoirs

As the global demand for energy escalates, the depletion of conventional oil and gas reserves has necessitated a shift towards unconventional reservoirs. These reservoirs, however, present significant challenges for oil recovery due to their complex rock properties, compositional heterogeneity, small pore throat size, low permeability, and low fluid mobility. Traditional methods, such as the injection of chemical agents to alter the oil-water interfacial properties, have proven less effective due to the intricacies of unconventional reservoirs. Moreover, while fracturing technologies can enhance permeability to some extent, they are yet to overcome issues of rapid production decline and final recovery rates below 10%. Nanomaterials, owing to their nanoscale dimensions and high surface-to-volume ratio, present a promising avenue for improving oil recovery. Their high surface energy enables easy adsorption onto solid surfaces or water/oil interfaces, suggesting potential for enhancing recovery in unconventional reservoirs. This comprehensive review focuses on the role and mechanisms of nanomaterials in improving oil recovery in unconventional reservoirs. It discusses a plethora of mechanisms including reduction of interfacial tension, alteration of wettability, stabilization of foam, emulsification, increase in solubility, improvement of oil flowability, and enhancement of spontaneous imbibition. Each mechanism is critically examined, considering the influence of various factors on their effectiveness. This analysis provides a theoretical foundation for the application of nanomaterials in diverse reservoir environments. By appreciating and fully understanding these mechanisms, we can optimize the performance advantages of nanomaterials, paving the way for more efficient and sustainable extraction techniques in unconventional reservoirs.