Response Surface Optimization of Water-Based Drilling Mud Viscosity Using Titanium Dioxide–Graphene Oxide Nanocomposite and Sodium Alginate Biopolymer

Drilling fluids play a critical role in efficient cuttings transport, suspension of drilled solids, hydraulic performance, and wellbore stability, making rheological control essential for safe and efficient drilling operations. However, conventional viscosifiers may have limited performance under demanding drilling conditions, motivating the development of nanocomposite–polymer systems with enhanced rheological tunability. The work in this article explores the viscosities of drilling fluid following the incorporation of a hydrothermally synthesized nanocomposite material formed through the interaction of titanium and graphene oxide, and a biopolymer, sodium alginate. A response surface methodology (RSM) approach based on concentration was employed to systematically observe the effects of these two different entities on the viscosity of the drilling fluid. During testing, 13 experimental runs were conducted to assess the influence of particle concentration on plastic viscosity and apparent viscosity. A strong correlation was established between the experimental test runs and the predictive model generated using this RSM, with R2 = 96.30% (adjusted R2 = 93.65% and predicted R2 = 84.13%) for plastic viscosity and R2 = 96.97% (adjusted R2 = 94.80% and predicted R2 = 85.04%) for apparent viscosity, and all 95% relative errors below 15%. ANOVA showed that the nanocomposite concentration was the significant parameter with p-value < 0.05 in both plastic viscosity and apparent viscosity, whereas the linear effect of sodium alginate was not significant as it demonstrated p-values > 0.05. Increasing the nanocomposite from 0.35 to 3.5 g at 0.35 g of sodium alginate raised the predicted plastic viscosity from 9.55 to 23.95 cP (+150%) and the apparent viscosity from 18.83 to 38.03 cP (+101%). The graphene oxide provides the anchoring sites to TiO2 nanoparticles that ultimately increase the inter-particle contact and exert an influence on both the viscosities. Additionally, in aqueous media, TiO2 nanoparticles hydroxylate, thus forming hydrogen bonding with graphene oxide. This interaction reduces the slippage effect of TiO2 nanoparticles between the fluid layers and eventually increases the friction force of the system. Furthermore, the sodium alginate adsorbs onto the large surface area of the nanomaterial, minimizing nanoparticle aggregation and forming a stable suspension, which in turn increases the viscosity. However, the influence of the biopolymer was minimal compared with the nano-dimension nanocomposite material. Overall, the findings offer valuable insights into the synergistic effects of biopolymers and nanocomposites in improving the lifting and transportation of drill cuttings, and in mitigating wellbore instability issues.