Biodiversity and Potential Activity of Microorganisms in Underground Gas Storage Horizons

The share of molecular hydrogen as a source of green energy is currently significantly increasing. It is proposed to use existing underground natural gas storage facilities to store large volumes of hydrogen. In Russia, depleted oil and gas fields (DOGFs) and deep aquifers are used for natural gas storage. The purpose of this work was to determine microbial diversity in DOGF and deep aquifers by cultural and 16S rRNA gene-based approaches and the effect of H-2 on the growth of microorganisms from the underground gas storage (UGS) horizons. The composition of the microbial community inhabiting the formation water of the Peschano-Umetskoe depleted oil and gas reservoir was typical for microbial communities of oil reservoirs and included bacteria of the phyla Bacillota (Dethiosulfatibacter, Defluviitalea, Acetobacterium, Syntrophobotulus), Actinobacteriota (Dietzia, Rhodococcus), Spirochaetota (Sphaerochaeta), Pseudomonadota (Shewanella), and Bacteroidota (Petrimonas), together with methanogenic archaea of the phylum Euryarchaeota (Methanobacterium). In some formation water samples, the share of methanogens of the genus Methanobacterium reached 61.6% of the total community; these hydrogen-utilizing organisms may contribute to the formation of methane in the reservoirs used for the storage of molecular hydrogen. Microbial communities of UGSs located in aquifers were less diverse and abundant. Cultivable hydrogenotrophic sulfate-reducing, homoacetogenic, and methanogenic prokaryotes were retrieved from the studied aquifers and from the DOGF used for gas storage. Microorganisms present in the condensation and reservoir waters of the UGS facilities can influence the composition of the water and gas phase, and affect the host rocks and borehole equipment.

Automated summary

The share of molecular hydrogen as green energy is increasing, and the use of existing underground natural gas storage facilities for hydrogen storage is proposed. Microbial diversity in depleted oil and gas fields and deep aquifers were studied, and the effect of hydrogen on microorganisms in underground gas storage was investigated. The findings show that microbial communities in the formation water of depleted oil and gas reservoirs are diverse and include hydrogen-utilizing microorganisms. Microbial communities in aquifers and gas storage facilities are less diverse. Microorganisms in the water of gas storage facilities can affect the water and gas composition, as well as the host rocks and equipment.