Experimental Evaluation of Low-Solid Water-Based Drilling Fluids for Mitigating Formation Damage

Abstract Despite significant advancements in drilling fluid technology, the issue of formation damage caused by drilling and completion fluids continues to pose a critical challenge to the productivity of hydrocarbon reservoirs. This study seeks to develop a cost-effective and environmentally sustainable drilling fluid with low solid content, offering improved solid control, simplified fluid maintenance, and minimal skin effects that impede fluid flow. Low-bentonite water-based drilling fluids (LB-WBM) were formulated by partially or fully substituting bentonite with cellulose nanoparticles (CNPs), specifically cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs). The concentration of CNPs ranged from 0.15 wt% to 0.60 wt%, while bentonite content was reduced from 6 wt% to 0 wt%, thereby lowering the total solid content from 13.34 wt% to 6.71 wt%. The influence of CNP concentration and morphology on rheological properties, filtrate loss, and filter cake characteristics, such as thickness, porosity, and permeability, was systematically evaluated. The findings demonstrated that the LB-WBM exhibited pronounced shear-thinning behavior. Fluids containing smaller CNCs exhibited lower viscosity, yield point, and gel strength, while their filter cakes were characterized by higher porosity and lower permeability compared to those with larger and elongated CNFs. Moreover, CNC-based fluids resulted in less reduction in porosity and permeability of ceramic disks than CNF-based fluids. These differences were attributed to the distinct morphologies of CNCs and CNFs, as well as their interactions with bentonite, which can be tailored to optimize fluid performance. Overall, this study underscores the potential of CNPs to advance the development of novel, environmentally friendly drilling fluid technologies, enabling more efficient and sustainable drilling operations.