Solution Properties of Hydrophobic Associative Polyacrylamide and the Relationship Between Rheological Characteristics at Similar Apparent Shear Viscosity and Improved Recovery

Polymer flooding has long been recognized as an established Enhanced Oil Recovery (EOR) technology. In recent years, a series of breakthrough laboratory experiments and pilot field tests have revealed that the use of viscoelastic polymers not only has the potential to overcome the performance bottlenecks of traditional polymer flooding, but also improves reservoirs' macroscopic volume sweep efficiency and microscopic pore‐scale displacement efficiency. This opens up new possibilities for updating EOR technologies. However, prior research has not adequately investigated the individual contribution of associative polymers' viscoelasticity to improved oil recovery. Against this background, three elastic systems were constructed in this study by varying the hydrophobic group content of associative polymers, and a comparative investigation was carried out with conventional HPAM. The solution properties under different hydrophobic group contents were characterized. After a series of studies, systems with similar apparent shear viscosity were selected and subjected to multiple elasticity and oil displacement performance tests. It was found that, among the four elastic systems with identical apparent shear viscosity, the first normal stress difference, deformation recovery capacity, and effective viscosity are positively correlated with oil displacement performance, among which effective viscosity shows the strongest linear correlation.