New insights into the interaction between asphaltene and hydrolyzed polyacrylamide at the oil-water interface based on emulsion stability

Asphaltene and hydrolyzed polyacrylamide (HPAM) are important components for stabilizing polymer-containing oil water/sludge in oilfield. In this study, the effects of asphaltenes concentration, HPAM concentration, pH, oil/water ratio and salinity on the storage stability and shear rheology of the emulsions were investigated. The results showed that the addition of HPAM could change the emulsion type from W/O to O/W, and the shear modulus of the emulsions stabilized by HPAM and asphaltenes were 10 times lower than that of asphaltenes emulsions. As the pH increased from 4 to 11, the emulsion type changed from W/O to O/W and the shear modulus of the emulsion decreased by 2 orders of magnitude. The addition of inorganic salts destroyed the asphaltene interfacial film and reduced the stability of the emulsion. The interaction of amide and carboxylic acid groups in HPAM molecules with asphaltenes was investigated through interfacial properties. The carboxylic groups and amide groups of HPAM molecules could interact with the interfacial active components of asphaltenes and formed a carboxyl-asphaltene-amide complex unit, which made the asphaltene molecules anchorage on the HPAM molecular chain. This study is intended to provide a theoretical basis for the efficient and environmentally friendly treatment of polymer-containing oil water/sludge in oilfield. © 2022 Elsevier B.V.