Performance Evaluation of Iron Oxide and Graphite Nanoparticles in Water-Based Drilling Muds at HPHT Conditions

The compositions of drilling muds are tailored to fulfil the harsh requirements of a deep wellbore environment. The fluid loss into the formations causes borehole instability and hinders the drilling operation's performance. The decrease in rheological characteristics influences carrying capacity. Nanoparticles have the ability to block the nanopores present in clay and limit fluid loss in formations and maintain drilling mud stability. This study investigates the capacity of iron oxide and graphite nanoparticles to affect the fluid loss characteristics and rheological features of a water-based drilling mud under HPHT conditions. To study rheological parameters, the Discovery Hybrid rheometer was used to determine the rheological properties of drilling muds containing nanoparticles in the concentration of 0.5 lb/bbl in a base drilling mud composed of 10 lb/bbl bentonite and 0.5 lb/bbl XC polymer. The experimental data were fitted to the Bingham Plastic model to study rheological parameters. API filtration test was performed to study the fluid loss volume of each drilling mud formulation. The linear swelling inhibition test showed that iron oxide and graphite particles reduced the swelling of bentonite. A significant improvement in rheological properties was observed for nanoparticles specifically with the addition of iron oxide (Fe₂O₃). The yield point and viscosity were increased significantly with iron oxide compared to graphite. The addition of nanoparticles maintained the stability of drilling muds at HPHT conditions and resulted in a stable rheological profile. A significant reduction in the fluid loss was also observed with iron oxide resulting in the lowest fluid loss compared to base and graphite mixed drilling muds. The use of nanoparticles along with high molecular weight polymer improved the fluid loss characteristics, rheological properties, and dispersion. This study reveals the potential use of nanoparticles as a water-based drilling mud additive with effective drilling operations and less formation damage in harsh conditions.