Hydrogen-Bonded amphiphilic polymer viscosity reducer for enhancing heavy oil Recovery: Synthesis, characterization and mechanism

• Amphiphilic polymer PTVR for heavy oil viscosity reduction was synthesized with functional monomers. • The amphiphilic polymer PTVR can emulsify heavy oil to form stable O/W emulsion. • The PTVR molecular can interact with asphaltenes and weaken their original hydrogen bonds. • The viscosity reduction mechanism of PTVR is explained in detail. With the gradual exploitation and consumption of conventional petroleum resources, heavy oil is considered as one of the alternative resources for energy supply. The key to the development of heavy oil is to reduce its viscosity. Herein, an amphiphilic polymer named PTVR was synthesized, which showed satisfactory viscosity reduction and recovery of heavy oil. The PTVR was copolymerized by acrylamide (AM), sodium p-styrenesulfonate (SSS) and two functional monomers lauryl methacrylate (LMA) and methyl-2-urea-4[1H]-pyrimidinone (MAUPy). P(AMS), P(ALS) with only one functional monomer, and P(AS) without functional monomer were also synthesized in order to study the effect of functional monomer on polymer properties. The structure of PTVR was identified by 1 H NMR, FT-IR, and TGA. The wettability, interfacial activity between heavy oil and PTVR, and viscosity reduction of heavy oil by PTVR were studied and compared with other three polymers. The results show that PTVR has more excellent properties. This is benefit by the synergistic effect of functional monomers MAUPy and LMA. MAUPy is a typical quadruple hydrogen-bonded monomer. It has the ability to insert into the lamellar aggregates of asphaltenes or resins, weakening or reorganizing the original hydrogen bond interaction. The LMA with long alkyl chain increases the affinity between polymer and heavy oil, which makes the polymer easier to emulsify heavy oil. The viscosity reduction rate of PTVR for heavy oil reached 92.4%, while P(AMS), P(ALS) and P(AS) were 82.8%, 80.7% and 67.2%, respectively. Furthermore, the sand-pack flooding experiment also confirmed that PTVR increased the recovery rate of heavy oil by 14.9%, while the control group was 11.7%, 10.7% and 8.6%, respectively. The application of the amphiphilic polymer PTVR has theoretical significance for enhancing heavy oil recovery.