Study On The Formation Of Hydrogen Sulfide In Steam Injection Well Of Gudao Oilfield

The crude oil thermal recovery makes the formation temperature exceed 200℃. The organic sulfides of heavy oil will occur aquathermolysis and produce H2 S. It is necessary to study the aquathermolysis of Gudao heavy oil because H2 S is very harmful to human, the environment and the oil extraction equipment. Recognizing the mechanism and reaction conditions of H2 S in aquathermolysis can provide evidence for the treatment of H2 S in the process of heavy oil thermal recovery.Taking Gudao heavy oil as object, the rule of non-catalytic aquathermolysis was systematically investigated. The effects of reaction temperature, water content and reaction time on the viscosity, composition, sulfur content were studied in detail, and the generating rule of hydrogen sulfide was mainly studied. The catalysis of minerals and transition metal ions on aquathermolysis was also studied. Compared with other metal ions used in the experiments, Ni2+ was the best catalyst. The concentration of hydrogen sulfide with time was detected when Ni2+ was added into the reaction system. Some kind of mercaptan, thioether and thiophene was added into the system to research the contributions on the hydrogen sulfide of different sulfide. The effects of rection temperature and concentration on aquathermolysis of dibenzyl sulfide were investigated in detail.The research showed that the optimized reaction condition is 260℃ for temperature, 20wt% for water content and 30 hours for time. Rising the reaction temperature, increasing the water content or extending the reaction time can reduce the viscosity, make the amount of saturate and aromatic increase, and that of resin and asphaltene decrease. Also, the sulfur content of the heavy oil decreased and the concentration of hydrogen sulfide increased. When catalyst was added into the reaction system, aquathermolysis was promoted. Ni2+ was the best catalyst in the series of metal ions used in the experiments. Compared to no catalyst, adding Ni2+ in reaction system can increase viscosity reduction rate by about 20%. Also, the yield of gases increased and the concentration of hydrogen sulfide decreased. Compared to the sulfide used in the experiments, dibenzyl sulfide made the largest contribution to hydrogen sulfide generation. Obvious aquathermolysis of dibenzyl sulfide occurred when the reaction temperature was over 260℃. As the concentration of dibenzyl sulfide increased from 0wt% to 5wt%, the highest concentration of hydrogen sulfide in reaction system increased from 1% to 38% or so, which indicated concentration made a great influence on dynamics of aquathermolysis.