Cellulose Nanoparticles as Modifiers for Rheology and Fluid Loss in Bentonite Water-based Fluids

TLDR

Rheological and filtration characteristics of drilling fluids are critical for drilling success. This study evaluates cellulose nanoparticles, including microfibrillated cellulose and cellulose nanocrystals, for improving rheology and filtration of bentonite water‑based drilling fluids. Cellulose nanocrystals were produced from microfibrillated cellulose via sulfuric acid hydrolysis. CNCs, smaller and more negatively charged than MFC, formed core‑shell structures with bentonite that yielded lower viscosity, better temperature stability, reduced fluid loss, and thinner filter cakes, and the addition of polyanionic cellulose further enhanced these properties.

Abstract

Rheological and filtration characteristics of drilling fluids are considered as two critical aspects to ensure the success of a drilling operation. This research demonstrates the effectiveness of cellulose nanoparticles (CNPs), including microfibrillated cellulose (MFC) and cellulose nanocrystals (CNCs) in enhancing the rheological and filtration performances of bentonite (BT) water-based drilling fluids (WDFs). CNCs were isolated from MFC through sulfuric acid hydrolysis. In comparison with MFC, the resultant CNCs had much smaller dimensions, more negative surface charge, higher stability in aqueous solutions, lower viscosity, and less evident shear thinning behavior. These differences resulted in the distinctive microstructures between MFC/BT- and CNC/BT-WDFs. A typical "core-shell" structure was created in CNC/BT-WDFs due to the strong surface interactions among BT layers, CNCs, and immobilized water molecules. However, a similar structure was not formed in MFC/BT-WDFs. As a result, CNC/BT-WDFs had superior rheological properties, higher temperature stability, less fluid loss volume, and thinner filter cakes than BT and MFC/BT-WDFs. Moreover, the presence of polyanionic cellulose (PAC) further improved the rheological and filtration performances of CNC/BT-WDFs, suggesting a synergistic effect between PAC and CNCs.