Influence of compositions of waxy crude oils on its electrorheological effects

Electric treatment has emerged as a promising technology to enhance the cold flowability of waxy crude oils, leveraging their intrinsic negative electrorheological (ER) effect through controlled electric fields. Experimental evidence indicates significant variability in treatment efficacy across different crude oil compositions. This study systematically investigates six waxy crude oils with resin-asphaltene contents spanning 4~23 wt%, revealing three distinct ER effect regimes: Low-complexity systems (<5 wt% resins/asphaltenes) exhibit non-monotonic viscosity reduction during wax precipitation, peaking near gelation temperature; Medium-complexity systems (5~12 wt%) demonstrate progressive viscosity attenuation from wax appearance temperature (WAT) to 10°C below gel point; High-complexity systems (>15 wt%) show negligible bulk viscosity modification (viscosity reduction<8%) but achieve remarkable structural strength reduction (yield stress reduction >65%). Mechanistic analysis through interfacial polarization theory reveals that ER performance is governed by wax-particle/charged-colloid interactions, modulated by both concentration-dependent dielectric properties and asphaltene aggregation states. The critical threshold at ≈15 wt% resin-asphaltene content corresponds to the percolation transition where conductive pathways dominate over dipole polarization effects. This study provides insights into the role of major compositions of crude oil in ER effects and contributes to the understanding of how electric treatment improves the flow properties of waxy crude oils.