A multi-purpose nanofluid strategy for flow assurance in challenging carbonate formations via simultaneous IFT reduction, asphaltene control, and wettability modification

Abstract Asphaltene deposition and unstable emulsions represent persistent flow assurance bottlenecks in enhanced oil recovery (EOR) from carbonate reservoirs, frequently inducing formation damage, pore throat plugging, and substantial productivity losses. Despite significant research efforts, no single nanofluid system has previously succeeded in simultaneously addressing the three critical flow assurance barriers interfacial tension (IFT), wettability, and asphaltene precipitation with quantified mechanistic evidence and rigorous statistical validation. This study presents a novel nanocomposite-based nanofluid, formulated in twice-diluted seawater (2DSW), which uniquely combines these three critical functionalities into a single, cost-effective formulation. To identify the optimal formulation, a comprehensive multi-scale experimental program was conducted, encompassing FTIR, zeta potential, thermal stability analysis, dynamic light scattering (DLS), core flooding, asphaltene dispersant test (ADT), asphaltene onset point (AOP) determination, emulsion stability assessment, and ATR-FTIR spectroscopy. All measurements were performed in triplicate ( n = 3) and subjected to rigorous statistical analysis using Student’s t-tests and one-way ANOVA with Tukey’s HSD post-hoc test ( p < 0.05). Through this systematic approach, 30 nanofluid compositions were screened across three brine types, and 0.03wt% nanocomposite in 2DSW was identified as the true global optimum, confirmed by quadratic regression (R 2 > 0.92) and multi-criteria decision analysis. This statistically validated formulation delivered consistent performance across all measured parameters, with IFT reduced from 14.2 to 1.73 mN/m ( p < 0.001), wettability shifted to strongly water-wet conditions (17.20°; p < 0.001), and zeta potential reaching − 56.28 mV, thereby confirming exceptional colloidal stability. The AOP advanced from 6% to 9.8% n-heptane, representing a 63% improvement ( p < 0.01), while the emulsion phase separation time extended to 90 min. Furthermore, the nanofluid flooding experiment demonstrated an incremental oil recovery of 34.5% of the original oil in place after conventional LoSal water flooding, with the nanofluid stage contributing 42.5% of the total 81% recovery factor. Meanwhile, ATR‑FTIR spectroscopy supplied direct molecular-scale evidence confirming that cation bridging drives the migration of polar asphaltene species toward the oil-water interface. Generally, this work constitutes the first demonstration of a single nanofluid system that concurrently optimizes IFT, wettability, and asphaltene control with comprehensive mechanistic and statistical validation, establishing a new benchmark for flow assurance in challenging carbonate formations.