Oil Has a Higher Methanogenic Potential than Coal in an Oil-Bearing Coal Seam

The presence of oil in coal seams from coal-oilsymbiosisareas poses a serious threat to the safe and efficient mining of coal.However, the information about the application of microbial technologyin oil-bearing coal seams was insufficient. In this study, the biologicalmethanogenic potential of coal and oil samples in an oil-bearing coalseam was analyzed by anaerobic incubation experiments. The resultsshowed that the biological methanogenic efficiency of the coal sampleincreased from 0.74 to 1.06 from day 20 to day 90, and the biologicalmethanogenic potential of the oil sample was about twice as high asthat of the coal sample after 40 days of incubation. The Shannon diversityand observed operational taxonomic unit (OTU) number of oil were lowerthan those in coal. The major genera in coal were Sedimentibacter, Lysinibacillus, Brevibacillus, etc., and the major genera in oil mainly included Enterobacter, Sporolactobacillus, and Bacillus. The methanogenic archaea in coal mainly belonged to the order Methanobacteriales, Methanocellales, Methanococcales, etc., and the methanogenic archaea in oilmainly belonged to the genera Methanobacterium, Methanobrevibacter, Methanoculleus, and Methanosarcina. In addition, metagenome analysis showedthat functional genes belonging to processes such as methane metabolism,microbial metabolism in different environments, and benzoate degradationwere in a higher abundance in the oil culture system, while genesbelonging to sulfur metabolism, biotin metabolism, and glutathionemetabolism were in a higher abundance in the coal culture system.The metabolites specific to coal samples mainly belonged to phenylpropanoids,polyketides, lipids, and lipid-like molecules; meanwhile, the metabolitesspecific to oil were mainly organic acids and their derivatives. Insummary, this study has a reference value for the elimination of oilfrom coal in oil-bearing coal seams and can be used to separate oilfrom oil-bearing coal seams and reduce the hazard brought by oil forcoal seam mining.

Automated summary

In this study, the biological methanogenic potential of coal and oil samples in an oil-bearing coal seam was analyzed. The results showed that the biological methanogenic efficiency of the coal sample increased over time, while the oil sample had a higher methanogenic potential. The microbial composition and metabolites specific to coal and oil were also investigated. This study provides valuable information for eliminating oil from coal in oil-bearing coal seams and reducing the risks associated with coal seam mining.