Investigation of inhibition mechanism of three deep eutectic solvents as potential shale inhibitors in water-based drilling fluids.

Graphical abstract Three deep eutectic solvents CM-DES, CP-DES and CIM-DES were evaluated for their great inhibitive capacity as potential shale inhibitors and all DESs exhibited superior inhibition performance than traditional inhibitor KCl and polyether diamine. Highlights • Three deep eutectic solvents CM-DES, CP-DES, CIM-DES were used as shale inhibitors. • Three DESs exhibited superior inhibitive properties than KCl and polyether diamine. • Both electrostatic interaction and hydrogen bonds to clay contributed to the inhibition. • CP-DES with the benzene ring presented the best inhibition performance. Abstract Three different deep eutectic solvents CM-DES, CP-DES and CIM-DES were synthesized and investigated for their novel use as shale inhibitors. Their inhibitive properties were evaluated and compared with traditional inhibitor KCl and currently popular inhibitor polyether diamine (PDA) through the inhibition tests such as bentonite inhibition test, linear swelling test, shale cuttings hot-rolling dispersion test, etc. All three DESs presented remarkable inhibition performance with lower concentrations and performed quite well even at high temperature (160 °C). Based on the results of scanning electron microscopy, Zeta potential measurement, surface tension measurement, thermogravimetric analysis and X-ray diffraction analysis, we proposed that the great inhibitive properties of DESs were probably attributed to the electrostatic attraction and hydrogen bond between DESs and clay, and the different structures of DESs resulted in different inhibitive capacity. With the excellent inhibitive properties, the synthesized DESs demonstrated potential application as effective shale inhibitors in water-based drilling fluids. [ABSTRACT FROM AUTHOR]