Modification of multi-walled carbon nanotubes and its effect on plugging the shale

Abstract

In this study, modified multi-walled carbon nanotubes (MMCNTs) were synthesized to plug the nanopores of shale oil and gas reservoirs. Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to test the characterization of MMCNTs. The effect of MMCNTs on shale surface wettability was examined by contact angle measurement, and the plugging property was tested by pressure transmission experiment and compressive strength experiment. The results show that MMCNTs could alter the shale surface wettability from lyophilic to hydrophobic as the water contact angle was increased to over 90°. It could prevent pressure transmission and enhance the shale strength effectively. Above all the experiments, MMCNTs plug the shale by altering the surface wettability and filling the shale nanopores with a special structure that possesses nano-size in width and micro-size in length. MMCNTs might provide a special avenue to plug the shale pore.