Study on the stability of heavy crude oil-in-water emulsions stabilized by two different hydrophobic amphiphilic polymers

摘要

Emulsification is an important oil recovery mechanism for amphiphilic polymer flooding, with a good viscosity reduction effect for heavy oil. Hence, the comparison study, aimed to elucidate the stabilization mechanism of amphiphilic polymers with single-branched and multi-branched hydrophobic groups, was proposed for the first time. Two amphiphilic polymers with different hydrophobic groups, poly (acrylamide/2-acryloylamino-2-methyl-1-propane sulfonic acid/N, N-dodecyl acrylamide) (PAAD) and poly (acrylamide/2-acryloylamino-2-methyl-1-propane sulfonic acid/N-dodecyl acrylamide) (PAAC), were employed to generate heavy crude oil-inwater emulsion. A laser particle size analyzer and Turbiscan Lab Expert stability analyzer were employed to characterize the stability of emulsions stabilized by the amphiphilic polymers. The results showed that the stability of emulsion stabilized by PAAD (Em-PD) was better than that of emulsion stabilized by PAAC (Em-PC). The particle size of Em-PD ranged from 0.9 mu m to 10.5 mu m while that of Em-PC ranged from 1.6 mu m to 16.5 mu m, which indicated that Em-PD showed a smaller average particle size and narrower distribution. It is found that the decline of oil-water interfacial tension is not the key factor for emulsion stability. The multi-branched amphiphilic polymer shows the enhancement of both the viscosity of dispersion medium and the interfacial viscoelasticity, producing the emulsion with stronger stability. The current work shows by designing the molecular structure of amphiphilic polymer to adjust its hydrophobicity can achieve the desired stability of heavy crude oil emulsion which is good for enhanced oil recovery.