Simulation Studies on the Role of Lauryl Betaine in Modulating the Stability of AOS Surfactant-Stabilized Foams Used in Enhanced Oil Recovery

Abstract

The stability of foam in the presence of oil is of fundamental interest in enhanced oil recovery processes using foam for mobility control. Experimentally, it is known that lauryl betaine (LB) increases foam stability of certain anionic surfactants, and LB is referred to as a foam booster. However, the molecular basis for this effect is not well understood. Using molecular dynamics simulations, here we study a system of LB and alpha olefin sulfonate (AOS-14), an anionic surfactant that is used as a foam stabilizer. We monitor the area per molecule, a quantity that correlates with the surface shear viscosity, and the surface dilatational modulus to infer the stability of the various mixtures. We find that the influence of LB is nonmonotonic: the area per molecule and surface dilatational modulus have a minimum and maximum, respectively, around 30% LB in the monolayer. We show that this net effect has its basis in two competing effects: the favorable interaction between LB and AOS-14 that tends to shrink the interface and the flexibility of the head group of LB that favors an expanded interface. The favorable interaction between LB and AOS serves to screen the interaction between the anionic surfactant molecules, effectively enhancing the interaction between them. Thus, mixing two different surfactants can result in a denser surfactant monolayer and potentially higher film stability.

A systematic approach to alkaline-surfactant-foam flooding of heavy oil: microfluidic assessment with a novel phase-behavior viscosity map

“…The surfactant solubility testing and surfactant-blend screening process are discussed in the Supplementary Information text S1. IOS is a commonly tested surfactant in chemical EOR studies and LB has been demonstrated to be a foam booster in the presence of oil [42][43][44][45] . The molecular weights of IOS and LB were estimated to be 350 g/ mol and 271.4 g/mol respectively.…”

Characterization of lauryl betaine foam in the Hele-Shaw cell at high foam qualities (80%–98%)

“…The increasing foam apparent viscosity with the addition of LB at the higher foam quality as compared to the surfactant solution without LB could be attributed to the elastic films generated by the addition of an amphoteric surfactant solution. The synergistic interaction between the anionic and the amphoteric surfactant molecules resulted in formation of a denser surfactant monolayer and potentially higher film stability (Wang et al 2017). This was also verified by measuring the surface tension of the individual surfactant solution A 100 and the mixed surfactant solution A 91 using a KRUSS Drop Shape Analyzer DSA 25.…”

“…The static stability of foams generated by different surfactant solutions in the Hele-Shaw cell was in order of: A 91 > A 100 > S 91 > A 73 > S 100. The blend of anionic and amphoteric surfactant resulted in a denser surfactant monolayer and potentially higher film stability (Wang et al 2017). Similar improvement in foam static stability, due to the blending of amphoteric surfactant with anionic Fig.…”

“…Electrostatic repulsion can also result from the interaction between the anionic surfactant and anionic center in betaine functional group. The enhanced electrostatic repulsion is expected to increase the disjoining pressure between the two interfaces preventing film coalescence and coarsening (Zhang et al 2005;Wang et al 2017). Simulation studies by different researchers showed that mixing of anionic and amphoteric surfactants could result in a denser surfactant monolayer and potentially higher film stability (Wang et al 2017).…”

Destabilization, Propagation, and Generation of Surfactant-Stabilized Foam during Crude Oil Displacement in Heterogeneous Model Porous Media

“…These surfactants are commonly used as strong foaming and foam boosting agents respectively 11,[37][38][39] . Specifically, when LB is added to AOS solutions, a synergistic effect occurs in which the overall packing density of the surfactant molecules on the interfaces increases resulting in greater resistance to distortion 40 therefore, a red dye was blended into this oil (Oil Red O, Sigma) for visualization purposes.…”