The Preparation and CO2-Resistant Performance of a Smart Responsive Polymer Gel for CO2 Flooding Channel Blocking

CO2 flooding is an effective technique for enhancing oil recovery in low-permeability reservoirs. However, it is often hindered by severe CO2 channeling. This challenge is particularly pronounced in near-wellbore regions with large pressure differentials and in fractured reservoirs, where high CO2 injection rates and rapid breakthrough require channel blocking systems with high mechanical strength and excellent CO2-resistant performance. In this work, a smart responsive polymer was synthesized and subsequently crosslinked with a highly active phenolic resin crosslinking agent to develop a smart responsive polymer gel channel blocking system. The resulting gel exhibits CO2-responsive strength enhancement and excellent CO2-resistant performance. The static and dynamic gelation behaviors, nonlinear rheological properties, CO2-resistant performance, channel blocking, and enhanced oil recovery performance of the smart responsive polymer gel were systematically investigated. The results demonstrate that the polymer gel maintains good structural stability during dynamic transport in the reservoir and does not undergo significant strength degradation under shear conditions. Moreover, the smart responsive polymer gel exhibits excellent CO2-resistant performance within a temperature range of 80–110 °C, salinity up to 10 × 104 mg/L, and pressure up to 20 MPa. Moreover, the system shows a significant enhancement in channel blocking and enhanced oil recovery performance, highlighting its promising potential for effective CO2 flooding channel blocking in low-permeability reservoirs.