XJ-21菌株在胍胶压裂液体系中破胶驱油的复合性能研究

The study on functions of XJ-21 strain with both gel breaking and oil displacement in guar gum fracturing fluid system

摘要:

在储层压裂改造过程中，胍胶压裂液体系低温破胶难，储层改造效果差，是新疆油田油藏开发亟待解决的关键技术难题。本文针对这一技术难题，将微生物强化采油技术应用于压裂液体系中，从新疆油田吉7井区烧房沟组采集到油泥，通过对样品中微生物的富集培养及分离后，筛选得到一株能够高产生物表面活性剂的菌株，将其命名为XJ-21。结合菌落形态观察、革兰氏染色及16S rRNA序列分析结果，XJ-21菌株被鉴定为枯草芽孢杆菌（Bacillus subitlis）。傅里叶变换红外光谱（FTIR）分析确定XJ-21代谢产物中的生物表面活性剂与环脂肽类结构一致。XJ-21菌株与外源ZW-027菌株复配后，复配体系对油藏环境条件具有广泛适应性，不仅在温度为35~55 ℃的范围内可以产生生物酶使胍胶冻胶破胶，还可在50 ℃的条件下降低样品所在区块的原油黏度，降黏率可达95.45%。在水驱后，使用复配体系驱油与仅用水驱技术相比可以提高10.14%的驱油效率。

Abstract:

During the process of reservoir fracturing modifaction, several key technical problems need to be solved urgently in Xinjiang oilfield reservoir development, such as difficulties of breaking gum in guar gum fracturing fluid system under low temperature, and poor effect of reservoir modification. To solve these problems, Microbial Enhanced Oil Recovery technique was applied in guar gum fracturing fluid in the present study. The oil sludge was collected from the Shaofanggou group in Ji 7 block of Xinjiang Oilfield, and a strain, named XJ-21, that is capable of producing high-yield surfactant was obtained after enrichment culture, isolation and screening. This strain was identified as Bacillus subtilis according to its morphological, Gram staining and 16S rRNA sequence analysis. The structure of bio-surfactant in XJ-21 strain metabolites was characterized was a substance that is consistent with the structure of the lipid peptide after Fourier transform infrared spectroscopy (FT-IR) analysis. After combination of the XJ-21 strain with an exogenous strain ZW-027, the compound system has wide adaptability to reservoir environment. Under the conditions from 35~55 ℃, not only the jelly guar gum could be broken, but also the viscosity of crude oil in Xinjiang could be reduced. And the viscosity reduction rate reached 95.45% at 50 ℃ in the presence of compound system and the displacement efficiency can be increased by 10.14% on the basis of water flooding.