A review on parameters affecting nanoparticles stabilized foam performance based on recent analyses

In recent years, much attention has been paid to the addition of nanoparticles (NPs) into the surfactant foam structure to form durable foams. Although surfactant foam as an enhanced oil recovery (EOR) technique significantly increases the viscosity of the injected fluid compared to gas injection, it has been observed that the foam structure does not have the required stability in cases such as high temperatures and high salinity. Although NP addition increases stability, the extent of this increase depends on several parameters, including NP properties (i.e., size, type, surface wettability) and reservoir properties (i.e., salinity of formation water, presence of oil, reservoir temperature), process parameters (i.e., NP concentration and flow rate), synergistic effects between the surface charge of NPs and the net charge of surfactant, and NP loss in the porous medium. This study aims to review and summarize the findings of previous studies to conclude the effects of each of the parameters above on foam stability, identify differences, and determine gaps for future studies. Throughout this report, a study background is provided, followed by the concept of stability and how to determine it in different tests for NP-surfactant foam. Next, the mechanisms of increasing stability by NP addition are briefly presented. Lastly, previous findings related to the effect of each parameter on NP foam stability are presented and discussed. Although several detailed reviews of NP-stabilized foam have been published previously, the present study differs from them in that the effects of additional parameters were investigated by reviewing new findings. Moreover, an attempt has been made to discuss the effects of parameters from different angles and according to their role in the mechanisms of NP-stabilized foam, such as particle detachment energy and maximum capillary pressure. The findings of this review show that i) oil presence lowers foam stability, ii) increasing NP concentration as well as decreasing NP size, temperature, NP retention, and salinity lead to increased stability, and iii) for parameters including NP surface wettability, NP types, and shear rate/flow velocity there are optimum points that result in the best foam performance. NP loss in a porous medium is an economically damaging process that occurs through mechanisms including adsorption, mechanical entrapment and log-jamming, and particles settling due to gravity. Depending on the type of mechanism, the strategy for minimizing or removing the influence of these mechanisms differs. However, there is currently no way to determine and measure the contribution of each of these mechanisms to the total retention in dynamic tests, which could be a specific topic for future research.

Automated summary

Oil presence decreases foam stability, while increasing NP concentration, decreasing NP size, temperature, NP retention, and salinity lead to increased stability. Optimum points exist for parameters like NP surface wettability, NP types, and shear rate/flow velocity for best foam performance. NP loss in a porous medium is an economically damaging process, and identifying mechanisms and strategies for minimizing their influence is crucial for future research.