含硫注采系统生物群落结构与硫化物含量影响因素分析

Analysis of biological community structure and factors influencing sulfide content in sulfur-bearing injection-production systems

目的为高效开展H2S防治,对靖边采油厂杨米涧区块“注水-采油”系统微生物群落进行结构分析与功能预测,并对硫化物生成关键因素开展分析研究。方法利用NovaSeq6000高通量测序方法对比了采出水、集输、水处理、注水4个阶段的水样生物群落差异性,利用FaPROTAX菌群功能分析方法对上述水样进行功能预测分析。结果①含硫油井中的脱硫菌门占比为16.7%~43.0%,显著高于集输、水处理和注水阶段,说明地层温度适宜的厌氧环境适于硫酸盐还原菌(SRB)生长繁殖,是产生H2S的主要原因;②含硫井O.3.1水样SRB和硝酸盐还原菌(NRB)在菌群中占比分别为33.02%和21.2%,但硝酸盐还原作用占比达到硫酸盐还原作用的2.3倍以上,说明NRB的存在对SRB具有明显的抑制作用。结论持续配注硝酸盐质量浓度高于40 mg/L以上的注水,可显著抑制SRB生长,减少H2S的产生,保障现场安全生产。

Objectives To prevent and control H_(2)S efficiently,this study conducted structural analysis and functional prediction of the microbial community in the"water injection-oil extraction"system which is located in the Yangmijian block of Jingbian Oil Production Plant,and analyzed the key factors of sulfide generation.Methods The NovaSeq6000 high-throughput sequencing method was used to compare the differences in the microbial community structure of water samples from four stages:produced water,gathering and transportation,water treatment,and water injection.The FaPROTAX bacterial functional analysis method was used to predict the functions of these water samples.Results Firstly,the proportion of desulfurizing bacteria in sulfur-containing oil wells ranged from 16.7%to 43.0%,significantly higher than that in other stages,indicating that the anaerobic environment with suitable formation temperature is conducive to the growth and reproduction of sulfate-reducing bacteria(SRB),which is the main reason of hydrogen sulfide production.Secondly,in the water sample O.3.1 of the sulfur-containing well,the proportions of SRB and NRB in the bacterial community were 33.02%and 21.20%,respectively.However,the proportion of nitrate reduction function was more than 2.3 times higher than that of sulfate reduction,indicating that the presence of nitrate-reducing bacteria has a significant inhibitory effect on sulfate-reducing bacteria.Conclusions Lasting injection of water with nitrate mass concentration higher than 40 mg/L could significantly inhibit the growth of sulfate-reducing bacteria and reduce the production of hydrogen sulfide,thus ensuring the safety of on-site production.