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.