Water-alternating-CO₂ gas (WAG) flooding is a common technique to enhance oil recovery via improving CO₂ sweep efficiency, but serious gas channeling may still occur, especially in reservoirs with strong heterogeneity, due to a poor blocking capacity of aqueous slugs to the “channeling” pathway induced by their low viscosity. Herein, a copolymer whose aqueous solution viscosity can be increased by both heat and CO₂ was developed and added into the aqueous slug to control gas channeling and increase oil recovery during enhanced WAG processes. The copolymer was synthesized by grafting poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) onto the triblock copolymer, Pluronic F127, PEO₁₀₀-PPO₆₅-PEO₁₀₀. The aqueous copolymer solutions can be thickened/gelled by heating due to the formation of micelles as the physical cross-link and their entanglements even at a concentration as low as 0.2 wt%, and viscosified by bubbling CO₂ thanks to expanded copolymer coils caused by electrostatic repulsion-induced chain extension of protonated PDMAEMA chains. Notably, thermo- and CO₂-triggered viscosifying can work synergistically and they are completely reversible upon cyclically heating/cooling the copolymer solutions and bubbling/removing CO₂ into/from the aqueous phase, respectively. In WAG flooding tests using two parallel cores, gas channeling was mitigated by blocking high-permeability cores due to in-situ thermo-induced gelation and CO₂-triggered thickening of copolymer slugs, thus diverting chase fluids into unswept low-permeability cores and enhancing 21–22% total oil recovery than the conventional and HAPM-enhanced WAG modes. Importantly, owing to the characteristics of low initial viscosity, single component, and thermo-gelation, this dually-responsive copolymer possesses high injectivity and satisfactory gelation control. This work could enlighten the design of novel dual/multiple stimuli-thickening polymers used for channeling control and enhanced oil recovery.

交替注水CO ₂气（WAG）驱油是通过提高CO ₂吹扫效率来提高采收率的常用技术，但是由于水的封闭能力差，特别是在非均质性强的油藏中，仍可能发生严重的气窜现象低粘度导致的“通道化”途径。在本文中，开发了可以通过加热和CO ₂两者来提高水溶液粘度的共聚物，并将其添加到水性块料中，以控制气体通道并在增强的WAG过程中增加油的采收率。通过将聚（甲基丙烯酸2-（二甲基氨基）乙酯（PDMAEMA）接枝到三嵌段共聚物Pluronic F127，PEO ₁₀₀ -PPO ₆₅ -PEO上来合成共聚物₁₀₀。由于形成胶束作为物理交联剂和它们的缠结，即使在浓度低至0.2 wt％时，也可以通过加热使共聚物水溶液增稠/胶凝，并且由于起泡而导致的共聚物线圈膨胀，可通过鼓泡CO ₂使其增粘。静电排斥诱导质子化PDMAEMA链的链扩展。值得注意的是，热触发和CO ₂触发的增粘可以协同工作，并且分别在循环加热/冷却共聚物溶液以及将CO ₂起泡/从水相鼓泡/除去时，它们是完全可逆的。在使用两个平行岩心的WAG驱油测试中，由于原位阻塞了高渗透率岩心，从而缓解了气体通道热诱导的胶凝作用和CO ₂触发的共聚物段塞的增稠，因此将追赶液分流到未扫掠的低渗透岩心中，与常规和HAPM增强的WAG模式相比，可提高21-22％的总采油量。重要的是，由于低初始粘度，单一组分和热凝胶化的特性，这种双重反应共聚物具有高的注入性和令人满意的凝胶化控制。这项工作可以启发新颖的双重/多重增稠增稠剂聚合物的设计，用于通道控制和提高采油率。