Dilational Rheological Properties of Surfactants at the Crude Oil-Water Interface: The Effect of Branch-Preformed Particle Gels and Polymers.

The interfacial properties of a heterogeneous composite flooding system containing a surfactant fatty alcohol polyoxyethylene carboxylate (CEOC), branched-preformed particle gel (B-PPG), and polymer partly hydrolyzed polyacrylamide (HPAM) at the crude oil-water interface were investigated by a dilational rheology method. The results demonstrated that the CEOC molecules can form an elastic interfacial film with certain strength at the crude oil-water interface. The addition of HPAM to the CEOC solution has a detrimental effect on the interfacial film formed by CEOC molecules, leading to a decrease in the dilational modulus and an increase in the phase angle. Moreover, the addition of B-PPG to the CEOC solution also disrupts the stability and strength of the interfacial film of CEOC. In particular, linear HPAM with a lower steric hindrance is more likely to insert into the interfacial film of CEOC; thus, HPAM possesses a stronger destruction ability for the interfacial film of CEOC than B-PPG. When HPAM is compounded with B-PPG, a superimposed effect exists to cause more severe disruption for the interfacial film. The heterogeneous composite flooding system not only enhances oil recovery by increasing the viscosity of the bulk phase but also weakens the interfacial film to facilitate the post-treatment of the recovered crude oil. Thus, the heterogeneous composite flooding system exhibits promising prospects in practical application.