LAUSR

Abstract In recent years, developing high-performance shale inhibitors with excellent shale swelling and dispersion inhibition properties has attracted great interests in the drilling industry. 1-Octyl-3-methylimidazolium bromide (OMB), a common imidazolium-based ionic liquid, was introduced as a promising shale inhibitor. Shale hydration inhibition capacity was investigated via sodium bentonite (Na-BT) plate soaking test, linear swelling experiment and hot-rolling dispersion experiment. The inhibition mechanism was analyzed by Fourier transforms infrared spectroscopy (FT-IR) analysis, X-ray diffraction (XRD) analysis, thermogravimetric (TGA) analysis, contact angle test, zeta potential test and surface tension measurement. The results demonstrated the shale hydration inhibition property of OMB was obviously superior to other widely used shale inhibitors. OMB could be easily adsorbed onto sodium montmorillonite (MMT) through electrostatic interaction, and some interlayer water molecules were expelled due to its intercalation. Meanwhile, the surface of MMT became more hydrophobic after adsorbed by OMB, and an effective shield against water intrusion was formed. In addition, OMB could effectively reduce the surface tension even at low concentrations, and a lower capillary suction pressure could be beneficial for reducing fluid invasion. The results obtained from the work indicated that OMB had the potential to become a high-performance shale inhibitor for drilling shale formations.