Micromechanism of partially hydrolyzed polyacrylamide molecule agglomeration morphology and its impact on the stability of crude oil−water interfacial film

Based on the background of oilfield chemical flooding produced liquid treatment projects, to achieve new insight into the micromechanism of the impact of polymer molecules applied to enhanced oil recovery (EOR) technology on the crude oil−water interface behavior, different “crude oil/HPAM/produced water” interface simulation systems were constructed by regulating the polymerization degree and hydrolysis degree of partially hydrolyzed polyacrylamide (HPAM) and combining the composition and physical properties of oil and water phases. The simulated results showed that all simulation systems have a stable layer order and clear crude oil−water interface after dynamic relaxation equilibrium. HPAM molecules were agglomerated in different forms at the crude oil−water interface depending on the inorganic cations in the water phase and their own degree of polymerization and hydrolysis, and the order of inorganic cations aggravating the agglomeration was Ca2+>Na+>K+>Mg2+. The stability of the interfacial film was positively correlated with the gyration radius of the HPAM molecules. Unlike the continuous increase in the gyration radius of HPAM molecules with increasing polymerization degree, the effect of increasing hydrolysis degree on the stability of the crude oil−water interfacial film is concentrated in the range of 15–35%, the gyration radius of HPAM molecules no longer increases when the hydrolysis degree continues to increase, and the interfacial film stability no longer significantly changes.