Synthesis and evaluation of nanohybrid pour point depressants as flow improvers for waxy crude oils

Waxy crude oils are characterized by high paraffin content, which leads to elevated viscosity and pour-point temperatures, posing significant challenges during transportation and processing. The work investigated the effectiveness of pour point depressants (PPDs) in enhancing the flow properties of waxy crude oil by reducing its viscosity and pour point. Terpolymers were synthesized via free radical polymerization of vinyl imidazole, maleic anhydride and long-chain alkyl acrylates (C20). Nanohybrid polymers were developed by incorporating modified nanosilica, synthesized from rice husk ash. Characterization through FTIR, 1H NMR, XRD, SEM and GPC confirmed the successful synthesis and structural integrity of the polymers. The additives were tested on two waxy crude oils (R and W). Pour point measurements revealed reductions in pour point up to 9 °C with nanohybrids, outperforming conventional terpolymers. Rheological studies showed significant viscosity reduction (up to 83%) and yield stress decline, indicating improved flowability at low temperatures. Microscopic analysis confirmed the morphological transformation of wax crystals, while cold finger tests demonstrated high paraffin inhibition efficiencies up to 71% with NTP-1. Overall, nanohybrid PPDs exhibited superior performance compared to conventional additives, attributed to enhanced dispersion and interaction with wax crystals. These findings highlight the potential of nanotechnology-integrated polymers in mitigating wax deposition and ensuring flow assurance in crude oil pipelines. These innovations position the proposed nanohybrid PPDs as a new-generation, high-performance and sustainable solution for wax deposition mitigation in crude oil pipeline systems.