Green nanocomposite synthesis and application: Electrochemically exfoliated graphene-modified biopolymer as an effective clay swelling inhibitor for water-based drilling muds

Abstract

The expansion of shale formations causing wellbore instability is a costly challenge in drilling operations. To address this issue, researchers have explored the potential of graphene as a shale swelling inhibitor and fluid loss controller. However, the practical application of graphene has been hindered by settling and limited dispersion in drilling muds. In this study, we present a promising solution using low-cost graphene prepared through simple electrochemical exfoliation of graphite. The resulting graphene was further combined with a natural biopolymer to create a nanocomposite. The nanocomposite, known as electrochemically exfoliated graphene-modified Gum Arabic (GrO-ArG), was evaluated as a fluid loss controller and shale swelling inhibitor in water-based drilling muds. To assess its inhibition potential, linear swelling and capillary suction timer tests were employed using different concentrations of the nanocomposite. Additionally, the performance of the drilling mud was examined through rheology and fluid loss tests. The experimental outcomes revealed that modified graphene showed strong dispersion in the water compared to graphene with minimum settling with time. The modified graphene showed stable dispersion in different pH and salinity solutions. GrO-ArG prominently reduced the linear swelling of bentonite clay (Na-Ben). It was observed that the decline in linear swelling was the function of the concentration of GrO-ArG, such as 1 wt% of ArG-GrO-A and ArG-GrO-B reduced the linear swelling by 37.8% and 43.9% correspondingly as compared to deionized water. The zeta potential measurement confirms the adsorption of GrO-ArG with the Na-Ben. The addition of GrO-ArG also revealed a prominent decrease in fluid loss. After the addition of ArG-GrO-A and ArG-GrO-B, the fluid loss declined from 11.3 mL to 8.2 mL and 7.1 mL respectively. A decrease in shear stress was also observed due to the addition of GrO-ArG in the drilling mud. From the experimental findings, it can be inferred that GrO-ArG is a strong candidate that might serve as an alternate green clay swelling inhibitor and fluid loss controller for water-based drilling muds.