Synthesis, Introduction and Study of the Rheological Properties of a Novel Polymeric Surfactant and its Effect on Interfacial Tension in Different Salinity

The application of polymers is one of the key techniques in different improved oil recovery (IOR) methods, namely polymer flooding, surfactant-polymer flooding, and alkaline-surfactant-polymer (ASP) flooding. Contact between polymers and surfactants in the reservoir, however, may cause some interactions between the two materials, leading to undesirable changes in their performance. In addition, flooding with polymeric surfactants is an attractive solution to this problem. Moreover, polymeric surfactants, in which hydrophobic groups are attached to hydrophilic polymers, simultaneously exhibit some properties of polymers and surfactants such as increasing the viscosity of solution, reducing the interfacial tension between water and oil, and also changing the wettability of the reservoir rock. In this study, polyacrylamide is hydrolyzed and using a zwitterion hydrophobic group, a new zwitterionic polymeric surfactant is synthesized. FTIR and HNMR identification tests verified the success of the process. The impact of hydrolyzed polyacrylamide (HPAM) and zwitterionic polymeric surfactant on water-oil interfacial tension, fluid viscosity, and shear rate were measured in the presence of CaCl2, MgCl2, K2SO4, and NaCl. Our results show that while HPAM reduced the interfacial tension to 13.65 mN/m, hydrophobically modified zwitterionic polyacrylamide (HMZPAM) reduced interfacial tension to 4.41 mN/m. While in similar conditions Hydrolyzed polyacrylamide reduces the interfacial tension to 13.65 mN/m. In salinity of 10,000 Mg/L, the viscosity of HPAM and HMZPAM were measured as 62 cP and 174 cP respectively. HMZPAM also showed better properties in elevated salt concentrations and shear rates. Finally, at the shear rate of 400 S-1, the apparent viscosity of HPAM and HMZPAM were equal to 0.14 cP and 1.06 cP respectively.