Enhancing dewatering and desalination of crude oil: A comprehensive study on energy-efficient separation technology driven by electric–magnetic coupling field

The rapid development of shale oil and offshore oil extraction has exacerbated brine contamination in crude oil, presenting challenges for conventional electric dehydration and desalination processes. Electric-magnetic coupling technology emerges as a promising alternative, while its underlying mechanisms and economic viability remain underexplored. In this study, we coupled a stabilized magnetic field with a high-frequency (greater than 1 kHz) pulsed alternating current electric field, enhancing the critical coalescence condition of salty droplets across a concentration range of 8.25 to 18.65 g·L −1 . Molecular dynamics simulations based on oil–water interface reveal that this enhancement is attributed to a reduction in the density and transport rate of surface charge on the droplets, influenced by ion electro enrichment and migration, ultimately allowing the electric field force to be insufficient against the capillary forces driving coalescence. Additionally, emulsion separation experiments show that the electric–magnetic coupling field increased separation efficiency by 33 % compared to the original electric field, achieving a rapid reduction of water content in high-salinity emulsions to 0.5 wt% within 20 min (includes 10 min of synchronized coupled field action). Furthermore, results of the techno-economic calculations based on our developed electric–magnetic coupling separation system indicate that the coupled-field system demonstrated a 8.26 % reduction in total costs due to lower energy consumption, highlighting its economic advantages in lower interest rate and high electricity price scenarios. Our findings provide novel insights into droplet coalescence dynamics and interfacial responses, paving the way for energy-efficient dehydration and desalination of crude oil.