Experimental investigation of pyrrolidinium-based ionic liquid as shale swelling inhibitor for water-based drilling fluids

This study evaluated the potential of 1-ethyl-1-methylpyrrolidinium bromide (1E1MPyBr) ionic liquid as a shale swelling inhibitor for water-based mud. Firstly, a linear shale swelling test was conducted to evaluate the ionic liquid's ability to inhibit clay hydration. Moreover, a capillary suction time test was performed to determine the fluid absorbance potential. Besides, particle size distribution analysis and zeta potential were evaluated to determine the ionic liquid effect on the base mud's colloidal distribution and surface charge. Furthermore, the rheological and filtration properties of the ionic liquid-mixed drilling mud were investigated. Finally, The X-ray diffraction analysis was conducted to evaluate the inhibition mechanism. The findings of this study revealed that the incorporation of 0.3 wt% of pyrrolidinium-based ionic liquid into the drilling mud resulted in a 20% reduction in shale swelling behaviour compared to conventional bentonite mud. The observed increase in particle size, decrease in zeta potential, and lower capillary suction timer values demonstrated the clay inhibition potential of ionic liquids. Moreover, adding the ionic liquid to bentonite mixed with water-based mud led to higher fluid loss and decreased rheological properties. These effects were attributed to the intercalation of ionic liquids into the clay layers, which inhibited swelling and hydration and reduced the water absorbance capacity of clay. Besides, the tested ionic liquid showed corrosion inhibition potential. Based on these results, the pyrrolidinium-based ionic liquid is proffered as an efficient shale swelling inhibition additive for water-based mud.