Effects of nutrient injection on the Xinjiang oil field microbial community studied in a long core flooding simulation device

In this study, an 8 m long core microbial flooding simulation device was built on a laboratory scale to study the dynamic changes of the indigenous microbial community structure in the Qizhong Block, Xinjiang oil field. During the MEOR, there was an approximate 34% upswing in oil extraction. Based on the 16S rRNA gene high-throughput sequencing, our results indicated that nutrition was one of the factors affecting the microbial communities in oil reservoirs. After the introduction of nutrients, hydrocarbon oxidizing bacteria became active, followed by the sequential activation of facultative anaerobes and anaerobic fermenting bacteria. This was consistent with the hypothesized succession of a microbial ecological "food chain" in the reservoir, which preliminarily supported the two-step activation theory for reservoir microbes transitioning from aerobic to anaerobic states. Furthermore, metagenomic results indicated that reservoir microorganisms had potential functions of hydrocarbon degradation, gas production and surfactant production. Understanding reservoir microbial communities and improving oil recovery are both aided by this work.

本研究搭建了实验室规模的8米长岩心微生物驱油模拟装置，以探究新疆油田七中区块原位微生物群落结构的动态变化。在微生物强化采油（Microbial Enhanced Oil Recovery, MEOR）过程中，原油采收率提升约34%。基于16S核糖体RNA（16S rRNA）基因高通量测序结果，本研究发现营养物质是影响油藏微生物群落的关键因素之一。添加营养物质后，烃类氧化菌率先被激活，随后兼性厌氧菌与厌氧发酵菌依次被激活。该结果与油藏内微生物生态“食物链”的演替假说相符，初步验证了油藏微生物从有氧到厌氧状态的两步激活理论。此外，宏基因组学分析结果显示，油藏微生物具备烃类降解、产气以及产表面活性剂的潜在功能。本研究有助于深化对油藏微生物群落的认知，并助力原油采收率的提升。