Partially aminated acrylic acid grafted activated carbon as inexpensive shale hydration inhibitor

In this work, we report the preparation of a novel partially aminated and inexpensive water-soluble acrylic acid grafted activated carbon represented as C-g-AA-NH₂ for efficient inhibition of shale hydration. The as-prepared C-AA-NH₂ was subjected to Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR), and thermal gravimetric analysis (TGA). This was followed by an evaluation of the capability of the material to inhibit shale through various tests including anti-swelling, shale recovery, and immersion tests. Our results indicated that 2% of C-g-AA-NH₂ drastically reduced water invasion into shale by combining plugging property of the core-centered carbon nanoparticles with the inhibition ability of the partially aminated acrylic acid component by adsorption on the clay surface through hydrogen bonding. In this manner, the plugging of the pore throat of the interlayer spacing of the shale formation could easily be achieved. This approach could significantly control fluid loss, reduce permeability and filtrate volume of drilling mud by forming a thin film on the formation surface due to the nano-nature of the carbon component of the polymer.