Analysis Of Microbial Communities In Different Areas Of Oilfield By Metagenomic

With the rapid development of high throughput sequencing technology,the use of metagenomic technology to study microbial communities in reservoir environment has gradually become a hot topic.Previous studies have shown that microorganisms existing in oil reservoirs and oil production environments have adapted to such extreme environments because of their long-term existence in such harsh natural environments as reservoirs with high temperature and pressure.Therefore,it is clear that the dominant microorganisms in different stages of the process of crude oil exploitation are the types and changes of microorganisms in the environment.The situation can help us to better formulate strategies and methods conducive to crude oil exploitation activities.In recent years,the development of macrogenomics technology enables us to directly extract all microorganisms in the environment for sequencing and analysis.Using the marker gene data of microorganisms in these communities,we can analyze the composition differences of specific species between these samples or sample groups and identify the function of microbial communities.It can provide constructive opinions for actual crude oil production.This thesis mainly focuses on the metagenomic technology and uses 16 S rRNA sequencing method to analyze the unexploited reservoir blocks and different environmental samples in the process of crude oil extraction.The main work of this thesis is as follows:Microbial communities in core samples,oil samples from production wells in reservoirs and sludge samples in production pipelines and tanks were sequenced by metagenomic technology.By analyzing the alpha diversity and beta diversity among samples,the differences of microbial community structure among the three groups of samples were analyzed in detail,and it was found that the species richness diversity of each sample group decreased gradually from pre-mining to exploitation and then to residual oil sludge.Through in-depth analysis of the specific species contained in different sample communities,we find that there are many microbial species beneficial to the oil industry in the microbial communities associated with these reservoirs.It includes Agrobacterium and Corynebacteria with biological desulfurization function,Bacillus,Burkholderia,Pseudomonas and Serratia with biological denitrification function,Bacillus and Pseudomonas with biological denitrification function,and Bacillus and Pseudomonas with biological denitrification function.Some microorganisms can reduce crude oil viscosity and increase crude oil production.In addition to the detailed analysis of the potential functions of microorganisms in each sample mentioned above,the functional analysis of microbial communities in all samples was also made.We found that the functional genes of these samples were mainly concentrated in metabolism,genetic information processing and environmental information processing.Previous potential functions of specific bacterial species are consistent with the reservoir environment.In this thesis,the microbial community structure in different petroleum environments was studied by using the current popular metagenomic sequencing technology.Through species analysis,cluster analysis and PCoA analysis,the classification of microbial species,functional differences of microbial communities and species diversity among samples in different environments in the oilfield were revealed.Secondly,through the analysis of main species,the abundance changes of dominant microorganisms in different sample groups were revealed.Finally,the potential ability of endogenous microorganisms to improve oil quality and reduce production costs is analyzed by tapping the functions of endogenous microorganisms.Sample function analysis was used to reveal the characteristics of gene function in the environment.These results have deepened our understanding of microorganisms in reservoir-related environments.It provides constructive suggestions for subsequent oil exploitation and activation of endogenous microorganisms.