Enhanced oil recovery from fractured carbonate reservoirs using nanoparticles with low salinity water and surfactant: A review on experimental and simulation studies

Nearly half of the world's oil reserves are found in carbonate reservoirs, which have heterogeneous formation characteristics and are naturally fractured. Because of the permeability contrast between the matrix and fracture network in these reservoirs, primary and secondary oil recovery processes are ineffective. Consequently, there has been a growing interest in enhanced oil recovery (EOR) from fractured carbonate reservoirs (FCRs) over the past years and many successful attempts have involved the use of different thermal or non-thermal EOR methods to improve oil recovery. Nonetheless, many researchers have recently directed their studies towards the use of low salinity water (LSW), nanopartides (NPs), and surfactant (LNS) as EOR agents in carbonates because they are environmentally friendly and incur low costs. Several studies have reported the successful application of the solutions of LSW, NPs, and surfactants either as individual solutions or in combinations, to carbonate formations. The challenges associated with their implementations such as fines migration for LSW flooding, surfactant adsorption onto the pore walls, and instability of NPs under harsh conditions, have also been identified in literature and addressed. However, relatively few investigations have been conducted on FCRs to study the effectiveness of these LNS EOR applications in the presence of fractures. This review, therefore, presents the reports of EOR in FCRs using LNS and identifies the mechanisms that influence these results. It has been shown that fines migration could either promote EOR or reduce recovery based on the occurrence of formation damage. In addition, surfactants with the tendency to form micro-emulsions will be efficient for EOR applications in FCRs. Finally, LNS solutions show promising results with emerging techniques such as alternating injection, which could be applied in FCRs. The findings from this study set the stage for future investigations into EOR in FCRs. (C) 2021 Elsevier B.V. All rights reserved.