Preparation and properties of nano-silica hybrid hydrophobic associated polyacrylamide for polymer flooding

Polymer flooding was one of the most commercial enhanced oil recovery (EOR) methods. It was the key to study novel polymer which had special properties for improving the oil displacement efficiency. In this study, a nano-hybrid polymer (PAAM@SNP) for polymer flooding was synthesized by in situ polymerization with monomers and silica nanoparticles (SNP). The composition, micro-morphology and rheological properties of PAAM and PAAM@SNP were characterized by FT-IR, 1H NMR, TEM, and rheometer. Compared with pure PAAM, the nano-hybrid polymers showed excellent viscoelastic, temperature resistance and shear resistance properties. The nano-hybrid polymer with the nanoparticle content of 1.5% w/w had the best performance. Improved performance of PAAM@SNP could be attributed to the rigid SNP was dispersed into the polymer to interact with the polymer molecules, which enhanced the network structure of PAAM@SNP and made the network structure of PAAM@SNP more complex. PAAM@SNP could make rocks tend to be water wet, which was good for oil displacement. In the enhanced oil recovery tests, nuclear magnetic resonance (NMR) visualization technology was combined with traditional core displacement experiments to study the effect of polymer flooding. The solution with a concentration of 0.1% w/w PAAM@SNP-1.5 increased oil recovery by 7.82% contrasting only 2.53% for the solution with a concentration of 0.15% w/w PAAM. Observation of cores during displacement by nuclear magnetic resonance imaging revealed that PAAM@SNP-1.5 reduced the mobility ratio oil to water and increased sweep efficiency notably. PAAM@SNP-1.5 had more obvious advantage in performance and more economical than PAAM, which made PAAM@SNP-1.5 have a better application in EOR.