Enhancing Heavy Crude Oil Flowability Using Vegetable Sesame Oil Extract as Bio-additives

The present study evaluated the effectiveness of a blend of dimethyl ketone (DMK) and methyl esters extracted from vegetable sesame oil (VSO) as a flow improver. The rheological impact of the additive on crude oil was assessed at various ratios (500, 1000, and 1500 ppm), shear rates (1.86–233 s⁻¹), and temperatures (5–30 °C). This study employed three models, Bingham plastic, power law, and Herschel–Bulkley, to evaluate the experimental data and determine the consistency factor and flow index of the oil samples considered. The average viscosity reduction (VR), thermal effects, activation energy, and yield stress of the additive were also assessed. The findings revealed that the blend enhanced crude oil flowability at low temperatures. Furthermore, at 1500 ppm and 1.86 and 46.5 s⁻¹ shear rates, the viscosity was diminished to 90.5% and 89.8%, respectively. The viscosity reduction was more significant at and over 100 s⁻¹ shear rates at temperatures up to 30 °C. Increasing dosage and temperature decreased yield stress and activation energy, \(E_{{\text{a}}}\), which reached 30.479 kJ mol⁻¹. The experimental data obtained in this study fitted the Herschel–Bulkley and power law models, approaching Newtonian behaviour at 1000 ppm. Moreover, the consistency index (k) of the crude oil incorporated with the additive diminished to 0.10386 and 0.029712, respectively. At 1500 ppm, the flow behaviour index (n) of the crude oil improved to 0.9665 and 0.9894 at 5 °C and 30 °C, respectively. The results demonstrated that the additive derived from natural seeds was an eco-friendly alternative flow improver.