Rheological Behaviors of Oil-Based Drilling Fluids in the Presence of Sawdust Charcoal Nanoparticles: A Molecular Dynamics Study

Drilling fluid performance is vital for operational efficiency, as it enhances the rate of penetration and ensures wellbore stability by preventing wellbore collapse. However, in harsh conditions (HPHT), the drilling efficiency and equipment longevity face significant threats. Specifically, the viscosity of drilling fluids decreases at high temperatures, exacerbating fluid loss. Mitigating fluid loss necessitates the deployment of temperature-stable additives, such as sawdust charcoal nanoparticles. The main objective of this study was to examine the rheological properties and filtration of bentonite, potassium chloride (KCl), and oil-based drilling fluids in the presence of sawdust charcoal nanoparticles using molecular dynamics simulations. Throughout the MD simulation, the changes in physical quantities, such as mean square displacement, shear stress, interaction energy, and viscosity, were analyzed. The main qualitative finding was that an increase in the initial temperature of the atomic sample enhanced atomic mobility; however, adding an additive to the initial structure reduced the sample’s mobility due to an increase in attractive interatomic forces. Key quantitative findings included MSD increase to 2.39 Å, indicating enhanced atomic oscillation, and the absorption of 28 atoms into the porous material, suggesting improved fluid penetration. Shear stress reached 69.92 Pa, reflecting interatomic forces, while the interaction energy converged to -14.85 kcal/mol, highlighting its role in penetration thresholds. Overall, the study emphasized the need to balance fluidity and penetration efficiency to optimize drilling fluids for practical applications. The findings contributed to cost-effective and efficient drilling practices in the oil industry while addressing challenges in fluid behavior at the nanoscale.