Comparative study on the inhibiting mechanism of inhibitor with primary amine groups and quaternary ammonium groups for sodium bentonite

Shale hydration and swelling is the main obstacle to the development of shale gas utilizing water-based drilling fluids (WBDFs). In this work, the inhibition mechanism of alkylammonium inhibitor and alkylamine inhibitor adsorbed on sodium bentonite (Na+Bent) are investigated using infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), zeta potential, particle size distribution tests, and thermogravimetry analysis (TGA). The results suggest that HTB and HMD can be inserted into the interlamination of Na+Bent and minimize the basal spacing compared to hydrated Na+Bent. HTB and HMD are inserted between the Na+Bent layers in a single-layer tiled manner and replace the sodium ions that are firmly fixed between the layers. Eventually, water molecules are removed from the interlayer Na+Bent. The interaction between the quaternary ammonium group and Na+Bent is more significant than between the primary amine group and Na+Bent. The inhibition performance suggests that HTB inhibits Na+Bent hydration and swelling more substantially than other inhibitors, indicating that the inhibition performance of the two quaternary ammonium groups is greater than that of the two primary amine groups. Therefore, HTB can be used as intercalation inhibition in WBDFs and has tremendous application value