Water-Redispersible Cellulose Nanofiber and Polyanionic Cellulose Hybrids for High-Performance Water-Based Drilling Fluids

Abstract

Cellulose nanofibers (CNFs) with nanoscale dimension, high aspect ratio, and easily modified surface chemistry show great potential as novel rheological and filtration modifiers in bentonite water-based drilling fluids (BT-WDFs). However, CNFs would suffer from poor redispersibility in an aqueous suspension if they were fully dried for transportation, storage, and field application. Herein, we report a simple, versatile, and scalable strategy to prepare water-redispersible CNFs through compounding them with a water-soluble, commercially available drilling fluid additive, polyanionic cellulose (PAC), and subsequent drying. The results revealed that the water redispersibility of CNF/PAC hybrids was dependent on the PAC's viscosity (i.e., low viscosity, LV; or regular viscosity, R) as well as drying method (i.e., oven drying, OD; or freeze-drying, FD). Among the obtained CNF/PAC hybrids, the CNF/PAC-R material prepared by FD exhibited optimal water redispersibility due to the enhanced suspending capacity of CNF suspension and the minimized capillary force. As a consequence, the CNF/PAC-R hybrids prepared by FD improved the rheological and filtration performance of BT-WDFs more pronouncedly than others, which could lead to better fluid carrying capacity for drilling cuttings and wellbore stability. The PAC acted not only as water-dispersible agents for CNFs but also as additives for modifying the rheological and filtration properties of BT-WDFs. PAC-coated cellulose nanofibers can be used as water-redispersible dry additive for drilling fluids with enhanced fluid performance.