Synergistic Control of Wax Deposition and Rheology in Niger Delta Crude Oil Using EVA Copolymer and Magnesium Oxide Nanofluid

Wax precipitation and deposition remain critical flow assurance challenges in offshore and onshore production systems. This study evaluates the effects of ethylene–vinyl acetate (EVA) copolymer, magnesium oxide (MgO) nanofluid, and their blend on the rheology of crude oil from field X in the Niger Delta. Baseline characterization (API gravity, pour point and cloud point) confirmed a heavy, high-viscosity crude prone to gelation at low temperature. Using ASTM-based protocols for density/API and pour/cloud points and a rotational viscometer, viscosity was measured across 5–25°C at multiple shear rates. Gas chromatography fingerprinting indicated reduced n-paraffins (C14–C18) with concentration of heavy ends. Relative to the blank sample, EVA alone produced a marked viscosity reduction; MgO nanofluid alone was also effective, but the EVA+MgO blend delivered the largest reduction across temperatures and shear rates. The blend lowered apparent viscosity by an order of magnitude at 300 rpm and improved low-temperature flow, with an observed pour-point reduction from −5°C to ≈ −12°C. These results support a synergistic mechanism in which EVA modifies wax crystallization while MgO-based nanodispersion aids dispersion and disrupts agglomeration, together mitigating gelation and deposition risk. Operational implications include lower restart pressures and extended pigging intervals for pipelines transporting waxy crude.