Graphene grafted with polyethyleneimine for enhanced shale inhibition in the water-based drilling fluid

Polyethyleneimine modified graphene (PEI-Gr) was prepared and characterized as a shale inhibitor. The PEI-Gr added water-based mud (PEI-Gr-WBM) displayed 25 %, 40 %, and 65 % higher shale dispersion recoveries as compared to KCl, traditional drilling mud and water respectively. The PEI-Gr treated shale material demonstrated stability against reactive action of water up to 24 h. Enhancement in the rheological features and fluid loss control of WBM was observed after the addition of PEI-Gr. The inhibition mechanism was investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-Ray spectroscopy, and thermogravimetric analysis. PEI carries the positively charged amines that help PEI-Gr to interact with the hydroxyl groups on the clay surface while possibly graphene plugs the clay pores. The possible intercalation with adsorption of PEI-Gr to the surface of clay assists in hindering water from entering the clay, aiding in the mitigation of swelling due to hydration.