Introduction: Crude oil is a complex mixture consisting of different hydrocarbons such as resins, asphaltenes, aromatics and paraffins. Wax deposition in oil pipelines is considered to be one of the most serious flow assurance problems.
Method: In order to obtain a pour point depressant with a better effect on Daqing waxy crude oil, a model oil containing Daqing paraffin was investigated. Polyoctadecyl acrylate was prepared by taking polymerization of octadecyl acrylate monomer under the corresponding reaction conditions. The pour point and viscosity were measured after adding the pour point depressant into the waxy model oil.
Results: The experimental results showed that the best pour point reduction effect of polyoctadecyl acrylate was achieved when the mass of octadecyl acrylate monomer was 40wt% of the total mass (the sum of the mass of solute octadecyl acrylate and solvent toluene), the reaction temperature was 80 °C, the reaction time was 6 h, and the amount of initiator was 0.15wt% under the condition that toluene was used as the solvent. The addition of polyoctadecyl acrylate effectively inhibits the appearance of wax crystals and makes the distribution of wax crystals more dispersed.
Conclusion: The optimal pour point depressant concentration was found to be 800 mg/kg. The alkyl side chains of polyoctadecyl acrylate allow co-crystallization with the waxy crystals and thus their dispersion, while its polar groups can weaken the interactions between the wax crystals.