Preparation and evaluation of double-hydrophilic diblock copolymer as viscosity reducers for heavy oil

摘要

In this work, a series of double-hydrophilic diblock copolymers of N-acryloylmorpholine (NAMO) and N,N-dialkylacrylamide are prepared as the additives for viscosity reduction, which could effectively interact with the asphaltenes and resins. The viscosity reduction effects of the types of N,N-dialkylacrylamide monomer (N,N-dimethyl acrylamide N,N-diethyl acrylamide) and degree of polymerization (DP) of poly(N,N-dialkylacrylamide) block in copolymers on heavy oil are tested with heavy oils with different viscosities. These viscosity reducers can work with small dosages (>25 mg L-1). The interfacial tension between oil and water is significantly weakened, and the aggregating structures of asphaltenes and resins are disassembled into smaller aggregates and covered with polymers with the addition of copolymers. The re-establishment of aggregates among polar components seems to be prevented, and the stability of the heavy oil/water emulsions is greatly enhanced as a result. All these results provide the prerequisites for water-soluble diblock copolymers working as viscosity reducers for various heavy oils.