Study On Biological Inhibition Technique Of H₂S In The Oil Gathering And Transportation System

H2S is a toxic gas, which cause serious harm to human body. In terms of the oil industry, H2S is widespread and it's harmful for the lives of occupationally exposed workers. With the expanding of exploration, exploitation and gathering in Changqing oilfield, it's a pressing matter of the moment to survey, prevent and manage H2S and other toxic and harmful gases。Therefore, to initiate a project to study H2S's gathering and transportation of biological inhibition in the oil gathering and transportation system is of great social and environmental benefit to the corporate's security environment and its protection and governance.And it's an important measure for Changqing oilfield to implement the scientific concept of development, promote a harmonious society and sustainable development.Based on the H2S's formation mechanism and influencing factors in the oil gathering and transportation system, we propose a bio-activity inhibition operation mode which use the equivalent spatial effect between environment-friendly bioactive inhibitor, SeO42- and B4O72-, and sulfate radical, rob the enzyme which produce H2S gas, isolate the sulfate-reducing bacteria through sulfate radical. Two kinds of bioactive inhibitor can significantly reduce the concentration of H2S gas in the system. When the bioactive inhibitor is SeO42-, its optimal dosage is 5mg/L, the time of bio-inhibition is about 5 days. When the bioactive inhibitor is B4O72-, the optimal dosage is 15mg/L, but we need to add auxiliary 25mg/L of humic acid vegetable gelatinplants to improve B4O72-'s speed of bio-inhibition and the time of inhibition could be controlled within 10 days. Considered the practical situation of gathering and transportation system, to adjust pH value appropriately to 8.0 can reduce the activity of SRB bacteria and control the generation of H2S, its mechanism based on the absorption of alkaline environment and the biotic environment's changes of SRB bacteria. The research analyses H2S gas treatment effect in the control system when bio-activity inhibition technique is used with bio-environment technique and points out that the complex technique with bio-activity inhibition technique and bio-environment technique suits to H2S gas control technology in Changqing Oilfield. The best pretreatment processing is to add a large number of reactant one time to each single well. When H2S gas was carried on in this technology, Aijiawan gathering and transportation station was research object, four on-site tests are contructed.The result shows that the technology can make sure the concentration of H2S gas in the system below 10mg/m3 which meets "the occupational exposure limits of workplace hazards " (GBZ2-2002) when the biological inhibitor is added to in 10 to 20 days. The application value of theory and methods that the project gains and the controllability of actual processing are proved.