Advances of self-assembly behaviors in polymer systems for improved oil recovery (IOR) in unconventional reservoirs.

Abstract

Traditional polymer systems including polymer and polymer gels face efficiency limitations in harsh unconventional reservoirs (low-permeability, high-temperature, high-salinity, serious-heterogenous, etc.) due to insufficient bulk/interfacial self-assembly capability. In recent decades, several self-assembly strengthening methods have been introduced into polymer systems to endow them bespoke functionalities and responsiveness suitable for different conditions. This review comprehensively analyzes advances in self-assembly-strengthened polymer systems for improved oil recovery (IOR), including molecular structure, synthesis methods and functional monomers from intrinsic principles and extrinsic functions and focusing on supramolecular interactions (hydrophobic association, host-guest inclusion, electrostatic forces), functional structures, and nanohybrid strategies. We detail how these approaches enhance bulk viscosity, interfacial activity, and conformance control in self-assembly polymer/gel systems while improving temperature/salinity resistance. And the practical efficacy is demonstrated through field validations in China, UAE, and Indonesia. Finally, the challenges and prospects for the self-assembly strengthening techniques for IOR in unconventional reservoirs are involved and systematically addressed. The deep understanding and precise regulation of self-assembly behaviors can open the way toward adaptive and evolutive polymer-based IOR technologies, a further step toward the cost-effective production of unconventional oil/gas resources.