Utilizing\nHigh Melting Point Long-Chain Fatty Acid\nBased CO<sub>2</sub> Response ILs for Suppression of CO<sub>2</sub> Gas Channeling and Clay Swelling

The\nwater-alternating-with-gas process is widely applied\nin oil\nrecovery but faces challenges such as gas channeling and clay swelling\nthat significantly reduce efficiency. To address these issues, a CO<sub>2</sub>-responsive liquid–solid transformation profile control\nagent (MA–D230) was designed. This agent was synthesized from\nmyristic acid (MA) and <i>O</i>,<i>O</i>′-bis­(2-aminopropyl)­polypropyleneglycol\n(D230) with a molar ratio of 2:1. MA was transferred from the solid\nto the liquid phase in D230 solution by electrostatic self-assembly.\nUpon CO<sub>2</sub> injection, MA was precipitated from the MA–D230\naqueous solution as a solid particle profile control agent, while\nD230 was protonated as a clay swelling inhibitor. The mechanisms of\nMA precipitation and D230 protonation were confirmed by the <sup>1</sup>H NMR analysis. After CO<sub>2</sub> injection, RE-MA precipitated\nfrom the MA–D230 aqueous solution, exhibiting the same crystal\nstructure, structural features, and melting point as its original\nstate. Furthermore, RE-MA can form in environments with salinity levels\nranging from 0 to 2000 ppm, while particle sizes in the micrometer\nrange are generated upon CO<sub>2</sub> injection. Moreover, the core\nflooding experiments further demonstrated that MA–D230 had\nan excellent ability to enhance oil recovery. In short, a new method\nwas proposed to solve the problems of gas channeling and clay swelling\nin CO<sub>2</sub> flooding during the WAG process.