关键词: 硫化氢；硫酸盐热化学还原；水热裂解反应；磺酸盐表面活性剂；稠油热采 

Abstract: Formation of H2S will bring great potential hazard to the safety of personnel and equipment in offshore oil fields. In order to determine the source of H2S in offshore heavy oil thermal recovery wells，the formation mechanism of H2S during thermal recovery development was investigated by conducting experiments. Simulated experimental study on the formation of H2S at different temperatures was carried out for the three reactions systems of heavy oil，heavy oil + distilled water，and heavy oil + water + core + methane. Besides， experiment was also conducted on the formation of H2S at high temperatures for sulfonate surfactant. The results show that for the heavy oil of Bohai S Oilfield，the concentration of H2S produced by the cracking and aquathermolysis of heavy oil increases with the increase in reaction temperature，and the organic gas produced is mostly the gas of light hydrocarbons below C5，with a small amount of C6+ gas. The aquathermolysis of heavy oil has caused the change in heavy oil composition. The contents of resin and asphaltene in heavy oil decrease，while the contents of saturated and aromatic components increase. This phenomenon becomes more obvious with the increase in reaction temperature. For the mixed system under study，at 200 ~ 300 ℃，aquathermolysis and TSR are dominant，which are the main sources of H2S；when the temperature reaches 350 ℃，cracking and TSR become dominant. At the same time，it is also found that it is very easy for sulfonate surfactant to produce H2S at high temperatures due to its instability at high temperatures. It is recommended that the use of sulfonate surfactant in the presence of steam be minimized in thermal recovery. 

Key words: hydrogen sulfide, thermochemical sulfate reduction, aquathermolysis, sulfonate surfactant, heavy oil thermal recovery