CO2-responsive polymer promoted by polyether to efficient viscosity increase for CO2 plugging

Abstract

A novel series of CO2-responsive polymers with unique hydrophobic structures were developed, capable of efficiently increasing viscosity in response to CO2 at low concentrations. These polymers, namely PAD-H, were synthesized by copolymerizing acrylamide, 2-(dimethylamino)ethyl methacrylate, and octadecyl polyoxyethylene ether methacrylate. In parallel, two comparative polymer sets were crafted, lacking the long polyether chains in their hydrophobic structures. DMAEMA imparts CO2-responsiveness through its tertiary amine groups, while the hydrophobic monomer contributes an alkyl structure with polyether long chains. These hydrophilic polyether long chains provide enhanced mobility to the hydrophobic alkyl chains, enabling lower concentration molecular hydrophobic association post CO2 exposure, thus leading to an increase in viscosity. This research delved into the mechanism of CO2-responsive viscosity increase, examining the impact of the polymer's intrinsic structure and external factors on its responsive behavior. Additionally, the polymer was applied in CO2 flooding, a crucial technique in carbon capture, utilization, and storage (CCUS). Simulated reservoir conditions were used to conduct in-situ CO2-responsive viscosity increase tests and CO2 gas channeling plugging experiments, substantially enhancing plugging efficiency. This advancement offers practical materials for addressing gas channeling in CO2 flooding and augments the technical methodologies for carbon utilization and storage within the CCUS framework.