Determination of Mass Transfer Rates of 3-Pentanone into Crude Oil at High Temperatures

3-Pentanone (3P) has been reported to promote a rapid shift in wettability of oil-wet reservoirs while largely preserving the water–oil interfacial tension. Since such behavior depends on 3P present at the oil–rock interface, understanding 3P transfer to the oil phase is important. Therefore, this study investigates the 3P mass transfer within the aqueous and oil phases and across their interface at high temperatures. To do so, molecular dynamics (MD) simulations and density functional theory combined with a COSMO-RS model were performed to understand the 3P behavior in oil–brine systems. Then, three experiments were conducted at 50, 60, and 74 °C by contacting an aqueous 3P solution with an oil layer. 3P concentrations were quantified by gas chromatography mass spectrometry. A mass-transfer model was developed to mimic the transient mass-transfer process and calibrated to the experimental data by simultaneously tuning the 3P mass-transfer coefficients in both phases. MD simulations showed 3P self-diffusion coefficient increasing from brine (1.62 × 10^–9 m²/s) to interface (1.75 × 10^–9 m²/s) and oil (2.05 × 10^–9 m²/s). The experiments showed rapid 3P uptake in all tests: more than 50% of 3P moved into the oil within 2.5 h, and 3P penetrated the entire oil column within 30 min. Early time transients were nearly identical, whereas late-time plateaus were temperature-dependent. The best-fit mass transfer coefficients obtained from the experimental data reflect the combined contributions of molecular diffusion and density-driven natural convection. The results showed that 3P can penetrate the oil phase quickly, which is relevant to applications where transport of 3P to the oil phase is important, including wettability modification and improved oil recovery.