Research Of Catalytic Degration Of Heavy Oil And Chemical Property Of Asphaltenes

Heavy oil is the substitute of conventional crude oil when it is depleted. But the heavy oil is difficult to be exploited and utilizated because of it's high viscosity. Down hole catalytic aquathermolysis reaction to decreasing its viscosity is a potential technology to resolve this puzzle.Liaohe heavy oil was used to study the feasibility of aquathermolusis reaction and seeking for suitable conditions during the process of the heavy oil upgrading in high-pressure batch reactor by imitating upgrading conditions at down well during steam injection. Upgrading effect was evaluated by comparing the composition changes before and after the reaction, average molecular weight, viscosity and the content of asphaltenes and resins. At the same time, properties of the asphaltenes were studied. The major conclutions are as following:(1) After quathermolysis reaction at 240℃for 24 hours while water to oil ratio is 0.5, viscosity of the heavy oil at 50℃decreased from 147.30 Pa·s to 130.40 Pa·s.(2) The sequence of transitional metal ions catalytic ability of aquathermolusis reaction and its decreasing of asphaltenes and resins are as following : Fe²⁺>Ni²⁺>Co²⁺>Ti⁴⁺>Cr³⁺>Mn²⁺>Cu²⁺>Zn²⁺. Aquathermolusis reaction at 260℃for 24 hours, the optimal concentrations of Fe²⁺ is 0.20%.(3) Calculating from the XRD results of asphaltenes, its dm, dr, La, Lc and Me are 2.3,2.9,27.9,3.6,6.9nm respectively.(4) The average mocular weights of asphaltene in toluene and in benzene are 3167 and 2404. It shows that asphaltene is associated in toluene and the palarity of the solvent could reduce the degree of association.(5) Dipole moments of the asphaltenes is 7.91tested by solvent method.(6) Precipitation point of the asphaltenes are 41% and 32% respectively when tested by viscosity method and surface tension method.