Graphene-Based Aqueous Drilling Muds as Efficient, Durable, and Environmentally Friendly Alternatives for Oil-Based Muds

Despite intense studies for numerous scenarios, the potential of graphene as a lubricant additive for oil and gas drilling applications remains rarely investigated. This study investigates the influence of graphene on the tribological performance of three different aqueous drilling fluids: distilled water(DW)-, artificial seawater (KCl brine)-, and potassium chloride (KCl) polymer water-based muds. The presence of graphene resulted in remarkably improved lubricity and wear-resistance in different drilling fluids. Specifically, pure distilled water demonstrated an excessive coefficient of friction (COF) of 1.30, while its mixture with 1.25–5.0 wt % graphene delivered COF values as low as 0.21, showing a reduction in friction by 70–85% and wear by 66–90%. As the graphene content increased in the KCl polymer water-based mud, the effectiveness of graphene in improving the lubricity and wear-resistance attenuated consistently. For saturated KCl brine, graphene in the same concentration range reduced the COF from 0.62 to 0.25, representing 46–60% reduction in COF and 23–61% reduction in wear. For KCl polymer water-based mud, the addition of graphene in the same concentration range was able to reduce the COF from 0.49 to a minimum of 0.33, representing a reduction in COF and wear by 22–33 and 68–98%, respectively. The higher tribological improvement of the graphene/distilled water is attributed to the filling of the abrasive grooves with graphene sheets. On the other hand, the presence of small particles in KCl brine- and KCl polymer water-based mud on the wear tracks prevents this phenomenon, causing lower tribological enhancements compared to distilled water. A possible explanation for the low friction and wear reduction is that the graphene, as a two-dimensional material, shears easily at the sliding contact interface. Furthermore, in the absence of abrasive micro–nanoparticles, the filling of the grooves with graphene sheets intensifies the tribological improvements.