Development Of Crude Oil Flow Improver And Its Mechanism

For offshore oil production platform, due to the limits of objective factors such as environment and site, the pour-point depressant used must meet the following aspects: the reagent itself has low condensation point and high flashing point, and can greatly reduce the condensation point of crude oil, maintain the pour-point depressing effect for a long time, keep stable at ambient temperature, and have good economic efficiency, etc. Specific to the transportation of pour-point depressant for piped crude oil on one platform of CNOOC, this paper filtered the EVA-type pour-point depressant additives; maleic anhydride and perfluorinated alkyl ethoxy ether alcohol and series of fatty acids were used to react with diethanolamine, diethylenetriamine, and polyethylene polyamine respectively to synthesize a series of surfactants as pour-point depressant additives; the influences of different additives on the pour-point depressing effect of EVA were investigated; the optimum pour-point depressant formula specific to the transportation of pour-point depressant for piped crude oil on one platform of CNOOC was found; viscometer, differential scanning calorimeter, and polarizing microscope and other instruments were used to help discuss the functional mechanism of pour-point depressants; in order to satisfy the requirements for use of offshore piped crude oil, research on the solvent system of pour-point depressants was also conducted.The experimental results showed that, EVA-3 had the best pour-point depressing effect. Through orthogonal experiment, the synthesis conditions of LMW(low molecular weight) polymer fluorinated surfactant were optimized, and the best reaction conditions were: 75℃(reaction temperature), 5:1(molar ratio), and 11000mg/kg(initiator dosage). Through orthogonal experiment, the synthesis conditions of erucic-acid polyene polyamine were optimized, and the best reaction conditions were: 150℃(reaction temperature), 2:1(molar ratio of erucic acid to polyethylene polyamine), and 1%(initiator dosage). The optimum pour-point depressant formula was obtained based on orthogonal experiment: the pour-point depressant, containing 88% xylene(mass fraction), 8% EVA, 2% erucic-acid polyene polyamine and 2% LMW polymer fluorinated surfactant, was added into crude oil by 1000mg/kg, making the crude oil’s condensation point 14℃, with a decline of 22℃. By mix design, the optimal solvent system was found: when the mass fraction of diesel oil was 61%, acetophenone 6%, xylene 24%, and benzyl alcohol 9%, EVA could dissolve in the mixed solvent best; when 8% EVA(mass fraction) dissolved in the mixed solvent, the mixture’s condensation point was 6℃ and the flashing point was 65℃, allowing the product to meet the using requirements on offshore platform.