Clay
swelling is one of the challenges faced by the oil industry.
Water-based drilling fluids (WBDF) are commonly used in drilling operations.
The selection of WBDF depends on its performance to improve rheology,
hydration properties, and fluid loss control. However, WBDF may result
in clay swelling in shale formations during drilling. In this work,
the impact of imidazolium-based ionic liquids on the clay swelling
was investigated. The studied ionic liquids have a common cation group,
1-allyl-3-methyllimidozium, but differ in anions (bromide, iodide,
chloride, and dicyanamide). The inhibition behavior of ionic liquids
was assessed by linear swell test, inhibition test, capillary suction
test, rheology, filtration, contact angle measurement, scanning electron
microscopy, and X-ray diffraction (XRD). It was observed that the
ionic liquids with different anions reduced the clay swelling. Ionic
liquids having a dicyanamide anion showed slightly better swelling
inhibition performance compared to other inhibitors. Scanning electron
microscopy images showed the water tendency to damage the clay structure,
displaying asymmetrical cavities and sharp edges. Nevertheless, the
addition of an ionic liquid to sodium bentonite (clay) exhibited fewer
cavities and a smooth and dense surface. XRD results showed the increase
in d-spacing, demonstrating the intercalation of ionic liquids in
interlayers of clay. The results showed that the clay swelling does
not strongly depend on the type of anion in imidazolium-based ILs.
However, the type of anion in imidazolium-based ILs influences the
rheological properties. The performance of ionic liquids was compared
with that of the commonly used clay inhibitor (sodium silicate) in
the oil and gas industry. ILs showed improved performance compared
to sodium silicate. The studied ionic liquids can be an attractive
alternative for commercial clay inhibitors as their impact on the
other properties of the drilling fluids was less compared to commercial
inhibitors.