Study On The Characteristics Of Sulfur Related Microorganisms In The Produced Water From Coalbed Methane Wells

In order to understand the generation and consumption mechanism of the secondary biogenic gas in the produced water of high coal reservoir,the sulfur related microbial geochemical reaction is explored.In this paper,the produced water from coalbed methane wells in the South Shizhuang block of Qinshui Basin is selected as the research object,and the collected water samples are tested for water routine anion and isotope.The results show that Na-HCO₃ and Na-HCO₃-Cl are the main types of water quality.The concentration of Ca²⁺,Mg²⁺,Cl^-,Na⁺in summer is higher than that in autumn and winter,while SO₄^2-is the opposite.The distribution range of?D is-68.14‰⁸4.93‰.?¹⁸O is-8.90‰¹1.50‰,?¹³C_DICIC is-13.04‰⁴0.37‰and most of them are positive.Using the ternary diagram analysis,it is concluded that the water produced by coalbed methane is affected by the dissolution of carbonate rock and iron sulfur mineral,and is strongly affected by the interaction of water and rock in the coal seam,with the integration of ancient sedimentary water.Cluster analysis and principal component analysis not only prove that the coal reservoir water is supplied by surface water and integrated by paleosedimentary seawater,but also prove that methane anaerobic oxidation and sulfate reduction have taken place through the opposite trend between?¹³C_DICIC and SO₄^2-,and the positive correlation between?¹³C_DICIC and CO₃^2-.At the same time,Fe²⁺,Mn²⁺,NO₃^-,SO₄^2-,SO₃^2-,S₂O₃^2-,Mg²⁺and As elements are selected as redox characteristic ions,and the redox zone of the study area is divided.Through 16S rDNA sequencing of the water samples from 41 coal-bed gas wells,it was found that the bacteria with the largest species abundance was Proteus,which was close to 80%.Among them,the bacteria with the widest distribution and the most species were gamma Proteobacteria,beta Proteobacteria and delta Proteobacteria.In general,the microbial species in the study area are mostly related to metabolism,and their distribution is affected by both physical conditions and hydrochemical conditions of coal reservoir.The dissolved methane isotopes in water are shown as biogenic gas in the methane genetic map,which proves that methane production and secondary biogenic gas have indeed occurred in the coal reservoir.Finally,combined with the geological structure and hydrological characteristics of Shizhuang South Block in the south of Qinshui Basin in the study area,the sulfur related microbial species and metabolic characteristics in different redox zones are summarized,and the sulfur cycle modes in the coal reservoir water under the reduction environment and in the coal reservoir water in the redox transition zone are respectively divided,and the sulfur cycle modes in the coal reservoir water in the high coal rank reservoir output water are explained Generation and consumption mechanism of secondary biogenic gas.