[NVim]Br and Poly([NVim]Br‐Co‐AM): Synthesis and Effects on Inhibiting Clay Swelling and Dispersion and the Mechanisms.

To solve the downhole problems correlated with clay hydration swelling and dispersion under high‐temperature conditions, a 1‐aminoethyl‐3‐vinylimidazolium bromide ([NVim]Br) and a [NVim]Br/acrylamide copolymer (poly([NVim]Br‐co‐AM)) are synthesized and used as inhibitors. The molecular structures of [NVim]Br and poly([NVim]Br‐co‐AM) are characterized by FT‐IR and 1H‐NMR. The inhibition properties of [NVim]Br and poly([NVim]Br‐co‐AM) are evaluated by free swelling and dispersion tests, linear swelling, hot roll recovery experiments and thermogravimetric analyses.The inhibition mechanisms were revealed by X‐ray diffraction, zeta potential, wettability analysis and ESEM observation. The results showed that both [NVim]Br and poly([NVim]Br‐co‐AM) has significantly superior inhibition performance compared with the common inhibitors KCl, polyether amine D230 and polyquaternium‐7. Both [NVim]Br and poly([NVim]Br‐co‐AM) can resist 250 °C. [NVim]Br performed excellently in inihibiting both crystalline and osmotic swelling, which depended on the strong electrostatic adsorption and hydrogen bonds of imidazole cations and primary amine in [NVim]+. Poly([NVim]Br‐co‐AM) exerted excellent inhibition by minimizing osmotic swelling, reducing hydrophilicity and increasing clay bonding. The results are important for understanding the rational design of novel efficient inhibitors for drilling high‐temperature shale formation. [ABSTRACT FROM AUTHOR]