Study On Catalytic Effects Of Orgainc Nickel And Iron On Visbreaking Of Heavy Oil From Shengli Oilfield

With the continuous development of global economy, light oil can not meet the needs of countries all over the world, while heavy oil is difficult to exploit due to its high viscosity and poor fluidity. Therefore, it's in the limelight to develop visbreaking techniques of heavy oil with high efficiency, low energy consumption and cost. At present, a catalytic visbreaking technique is receiving more attention in the visbreaking research activity. Water-solubility transition metal catalysts, oil-solubility transition metal catalysts, super acid catalysts and heteropoly acid catalysts have been reported to have visbreaking activity. In this paper, three organic transition metal catalysts, that is, nickel oleate, nickel 2,2'-bipyridine and iron 2,2'-bipyridine complexes, were prepared and used to reduce the viscosity of 1# and 2# heavy oil from Shengli oilfield. The results were obtained as follows:Under the conditions: reaction temperature of 240℃, pressure of 5~8 MPa, three organic nickel and iron catalysts were used to reduce viscosity of 1# heavy oil, respectively. Its viscosity was reduced by 63.0% by the nickel 2,2'-bipyridine complex catalyst when the mass ratio of catalyst to oil was 0.2% and the mass ratio of water to oil was 10%. The reduction of viscosity of oil without water could reach to 84.0% with the same mass ratio of catalyst to oil.Under the same reaction conditions, iron 2,2'-bipyridine complex catalyst could reduce the viscosity of 2# greatly, and the viscosity reduction was 71.1% when the mass ratio of catalyst to oil was 0.01% and the mass ratio of water to oil was 20%. With the same mass ratio of catalyst to oil, viscosity reduction of 2# oil without water was 86.2%. A series of characteristic methods have been used to investigate the mechanism of visbreaking of Shengli heavy oil. The gas produced by the visbreaking reactions was determined by GC and found to consist of H2S, CS2, COS, CH4, C2H6, C3H8, n-C4H10, i-C4H10, which proved that part of C-S bonds and C-C bonds in the compounds in heavy oil broke during the reaction process. In the gas, the amounts of H2S were more than CS2, COS. Using nickel and iron 2,2'-bipyridine, the gas after visbreaking reaction was composed of CH4 and C2H6. While using nickel oleate, the gas included CH4, C2H6, C3H8, n-C4H10, i-C4H10. The composition of the heavy oil before and after visbreaking reaction was determined using liquid-solid adsorption chromatography. The results revealed that amount of saturate in the oil increased, while that of aromatic, resin and asphaltene decreased after the visbreaking reaction of Shengli 1# heavy oil. As to Shengli 2# heavy oil, the amount of saturate and aromatic increased, while that of resin and asphaltene decreased after the visbreaking reaction. The IR spectra of saturate, aromatic, resin and alphaltene showed that the characteristic peaks of methyl, methylene and (CH2)n in saturate and aromatic were enhanced after visbreaking reactions,which accorded with the change in viscosity of the oil. While the characteristic peaks of methyl, methylene and organic sulfide in resin and alphaltene were weakened after visbreaking reactions, which proved that resin and alphaltene cracked.