Rheological investigation of smart polymer/carbon nanotube complex on properties of water-based drilling fluids

Carbon-based nano-materials and polymers are the most propitious materials proposed to cure the serious problems encountered in drilling operation. The aim of this study is to improve the essential properties of selected water-based drilling muds (WBMs) using a new synthesized complex of oxidized multi-walled carbon nanotube wrapped by polyethylene glycol (POCNT). A rotational rheometer and an API filter press were used to analyze the rheological and filtration properties of the drilling muds, and smart hydrophilic and hydrophobic behaviors were expected due to carboxylic bonds and PEG polymer chains. It has been shown that adding a relatively low amount of POCNT to selected water-based muds will lead to a significant improvement in rheological behaviors of the drilling fluid, and a noticeable reduction in their associated formation damage. Specifically, the presence of POCNT in WBMs has shown to enhance the viscosity, yield stress, and subsequently the carrying capacity of the drilling muds at several temperatures. Moreover, it has been indicated that this formulation could properly decrease the permeability of mud cake, and as a result, reduce the filtration volume of nanofluids compared with that of base fluid by up to 82%. At the end, the curve fitting analysis proves that the Herschel-Bulkley method better fits the rheological behaviors of this new nano drilling fluid.