吉木萨尔页岩油H2S成因分析

Causes analysis of hydrogen sulfide in Jimusar shale oil

关键词:  页岩油  H₂S  硫同位素  SRB  生物成因

Key words:  shale oil  hydrogen sulfide  sulfur isotope  sulfate-reducing bacteria(SRB)  biological cause

摘要:

目的 针对吉木萨尔页岩油生产过程中存在的H₂S问题,开展了H₂S成因分析。方法 对硫元素同位素和SRB种类、生物成因反应条件进行了分析。结果 实验表明,吉木萨尔页岩油H₂S为生物成因,产出液中SRB、SO2-₄含量与井口H₂S含量呈正相关, 通过16SrRNA技术鉴定出适宜30 ～40 ℃中温型的SRB 3种,适应60～100 ℃高温型的SRB 6种,在温度为35～100 ℃、矿化度为(0.2～8.0)×10⁴ mg/L、pH值为4～9范围内均可正常生长,满足生物成因的条件。SRB可依赖压裂液大量繁殖,促进了H₂S的形成。结论 针对生物成因,制定了以杀菌剂替代化学除硫剂的工艺,现场试验8井次,井口H₂S含量降至安全阈限值以下,同比除硫费用降低40.9%,为有效治理H₂S提供了依据。 

Abstract:

Objective In view of the hydrogen sulfide problem in the production process of Jimusar shale oil, the cause of hydrogen sulfide was analyzed. Methods The isotopes of sulfur element,sulfate-reducing bacteria species and the reaction conditions of biological cause were analyzed. Results The experiment showed that the tormation reason of hydrogen sulfide in Jimusar shale oil was biological cause, the content of sulfate-reducing bacteria and sulfurate ions in the output fluid were positively correlated with the concentration of hydrogen sulfide at the wellhead. Three kinds of medium-temperature sulfate-reducing bacteria suitable for 30-40 ℃ were identified through 16SrRNA technology, and six kinds of high temperature sulfate-reducing bacteria suitable for 60-100 ℃ were also determined. They can grow normally under the conditions of temperatures of 35-100 ℃, mineralization of (0.2-8.0)×10⁴ mg/L, and pH value of 4-9, which can meet the conditions of biological cause. Sulfate-reducing bacteria can multiply in large numbers by fracturing fluid and promote the formation of hydrogen sulfide. Conclusion sAiming at the biological cause, a process of replacing chemical sulfur remover with a fungicide was developed, and 8 wells were tested on site,the hydrogen sulfide concentration fell below the safety threshold, the cost of sulfur removal decreased by 40.9% compared with the same period,which provided a basis for effective treatment.