Cellulose nanofibrils as rheology modifier and fluid loss additive in water-based drilling fluids: Rheological properties, rheological modeling, and filtration mechanisms

This study aims to improve the rheological and filtration properties of water-based drilling fluids (WDFs) by using cellulose nanofibrils (CNFs), which are the critical parameters in drilling operation. Results showed that the incorporation of CNFs in WDFs effectively improved the rheological and filtration properties. The lathy and flexible CNFs was entangled with bentonite (BT) to form the intertwined CNFs-BT network structure in WDFs, leading to an enhanced viscosity, gel behavior, and temperature stability of WDFs. WDFs containing CNFs showed the superior rheological properties, including the yield stress, anti-deformation capacity and structural restructuring capacity, suggesting an increased capacity to transport the cuttings to the surface. The excellent shear-thinning behavior was due to the orientation movement of CNFs along the shear force. Moreover, the nanosized CNFs resulted in the low permeable filter cakes, leading to less fluid loss volume and final filtration rate. We revealed the fundamental insights into the rheological and filtration properties of WDFs containing CNFs, paving the way for the application of new eco-friendly drilling fluid. Data availability: Data will be made available on request.