Valorization of Iraqi desert sand into functional hydrophobic silica microparticles for heavy oil upgrading in a novel digital batch baffled viscosity reducer: Experimental investigation and predictive modeling

Heavy crude oil produced from the East Baghdad oilfield is currently transported mainly by trucks because of its high viscosity, which limits its pipeline transportation and increases operating costs. This study investigated a sustainable approach for improving the flowability of East Baghdad heavy crude oil using functional hydrophobic silica microparticles (FHS-MPs) prepared from naturally abundant Iraqi desert silica sand. The silica particles were surface-modified with 1-propanol to enhance their hydrophobicity and affinity toward the nonpolar hydrocarbon phase. The prepared particles were characterized using Fourier-transform infrared spectroscopy (FTIR) and water contact angle measurements to verify the successful surface modification. The effects of particle loading (0–500 ppm), and operating temperature (10–50 °C) on crude oil viscosity were systematically investigated using a novel digital batch baffled viscosity reducer. The used reducer was allowed controlled adjustment of temperature and stirring speed and contained four vertical baffles to boost bulk circulation and particle dispersion. The experimental results demonstrated that the hydrophobic silica microparticles significantly outperformed untreated silica by promoting stronger interactions with asphaltene aggregates and disrupting the viscoelastic network responsible for the high viscosity of heavy crude oil. The optimum operating condition was obtained at a particle loading of 400 ppm, achieving a 31 % viscosity reduction at 30 °C, whereas further increases in particle concentration reduced the improvement because of particle agglomeration. Increasing temperature further enhanced viscosity reduction through a synergistic effect with the hydrophobic particles. Comparative experiments exhibited that the baffled reducer conducted a maximum viscosity reduction of 31 %, compared with 26 % for the unbaffled design under the best conditions. An empirical predictive model was developed to correlate crude oil viscosity with particle loading and operating temperature, exhibiting excellent agreement with the experimental data (R 2 = 0.995). The proposed approach provides a simple and potentially low-cost strategy for boosting the flowability of Iraqi heavy crude oil. Although the present study was achieved at laboratory scale, the results create a basis for further examination of scale-up and potential pipeline applications.