Improving the performance of invert emulsion drilling fluid using boron nitride and graphene nanoplatelets for drilling of unconventional high-temperature shale formations

Drilling in deep unconventional shale formations is one of the most complex and challenging tasks. The success of the drilling operation in these formations is greatly reliant on the drilling fluid used. Oil-based drilling fluid is extensively used for its excellent performance in drilling troublesome shale formations. However, the stability of conventional additives in oil-based drilling fluid at high temperatures limits their use. These deteriorate at high-temperature conditions and can cause severe drilling problems. This research study aims to improve the performance of oil-based drilling fluid by developing a hybrid nano-based invert emulsion drilling fluid using graphene nanoplatelets and boron nitride nanomaterials. An extensive and comprehensive experimental study is performed to investigate and quantify the effect of these nanomaterials on the rheological and filtration properties of oil-based drilling fluid. In addition to that, electrical stability and viscoelastic characteristics are also investigated. Characterisation of nanomaterials is performed to analyse the morphology and purity. The formulated hybrid nano-drilling fluid demonstrates the improved rheological properties with enhanced filtration characteristics. The nanomaterials with a concentration of 0.2 ppb improve the plastic viscosity and yield point by 17 and 36, respectively. A maximum 60 reduction in filtrate loss is observed at 0.6 ppb. The nanomaterials also enhanced the viscoelastic properties and extended the linear viscoelastic range. Furthermore, the flow behaviour and rheological modelling are performed at varying temperatures (25�125 °C) and shear rates (0.1�1200 s�1). The obtained results suggest that the hybrid nano-drilling fluid exhibit non-Newtonian shear-thinning behaviour consistent with the Herschel�Bulkley model. © 2022 Elsevier B.V.