Bioinspired Self-Assembly Polymer Based on Nucleobase for Enhanced Oil Recovery

Polymer flooding is one of the most effective tertiary oil recovery technologies, which can significantly improve the sweep efficiency of the reservoir by injecting high-viscosity polymer solution. However, Conventional polymers are difficult to inject, easy to degrade after shearing, cause plugging in low-permeability reservoirs, functional monomers have potential environmental pollution risks, and limit its industrial application. In recent years, more and more attention has been paid to the development of adaptive supramolecular oil displacement materials from bio-based materials. Here, the bases of guanine and cytosine from ribonucleic acid are grafted onto polyacrylamide. With a multi-supramolecular interactions through synergistic hydrogen bonding and hydrophobic interactions, HPAM-C≡G-HPAM with excellent injectivity and high viscosity are developed to improve the recovery of low permeability reservoirs. Subsequently, HPAM-C≡G-HPAM was characterized by FT-IR, NMR, ESEM and DLS. The rheological test results show that the tackifying ability of the supramolecular system is much higher than that of polyacrylamide with the same molecular weight and has excellent shear resistance. In the laboratory core displacement experiment, the injection pressure of HPAM-C≡G-HPAM in low permeability core is only 1/3 of that of polyacrylamide with the same viscosity, and the oil recovery can be increased by 16.31%, The oil recovery can be increased by 10% under high temperature and high salinity conditions. Accordingly, HPAM-C≡G-HPAM has the potential to greatly enhance oil recovery in low permeability reservoirs.