Influence Factors of Nickel Salts as Catalysts on Aquathermolysis Reaction of Niujuanhu Oil

In high-temperature and high-pressure(HTHP)reaction kettle,with formic acid as hydrogen donor and nickel salt as catalytic system,the influence factors on aquathermolysis reaction of Niujuanhu oil were studied by considering the effects of different catalyst systems,crude oil properties and reaction temperature on oil viscosity reduction ratio and SARA changes.The results showed that viscosity reduction rate of nickel oleate,nickel naphthenate and nickel sulfate catalytic systems to stock tank oil was 65.3%,52.6% and 55.7%.Nickel oleate was selected as optimum catalytic system.After aquathermolysis catalytic reaction,the content of colloid and asphaltene decreased,and that of saturated hydrocarbons and aromatic hydrocarbons increased.The more content of heavy hydrocarbon in oil,the stronger aquathermolysis reaction,and the more favorable viscosity reduction of oil was.After aquathermolysis catalytic reaction,the viscosity reduction rate of residuum,stock tank oil and simulated formation oil was 90.41%,64.78% and 55.78% at 45℃.The content of colloid and asphaltene in crude oil was the basic root of aquathermolysis reaction.The conversion ratio of colloid and asphaltene converting into saturated hydrocarbon and aromatic hydrocarbon in residuum,stock tank oil and simulated formation oil was 36.50%,26.51% and 16.73%.The viscosity reduction rate of simulated formation oil was 56.43%,55.78%,48.23% and 14.14% at 280℃,220℃,180℃ and 100℃ reaction temperature.The optimum reaction temperature was 220℃.The macromolecule bond rupture of colloid and asphaltene into small molecule saturated hydrocarbons was the main reason of permanence viscosity reduction of crude oil during aquathermolysis reaction.