[Shift of Microbial Communities During the CO 2 -Brine-Sandstone Interaction Process].

In this study, the dynamic variation of the structure, functionality and biodiversity of indigenous microorganism during the CO2 -brine-sandstone interaction process was investigated using MiSeq sequencing techniques. The results indicated that some kinds of indigenous microorganisms could grow well under the extreme condition induced by CO2 -injection. After injection of CO2 , the species of indigenous microorganisms tended to be single and the relative abundance of Proteobacteria reached up to 99.77% after 6 months. The dominant species varied as follows: Pseudomonas sp., Citrobacter sp. and Brevundimonas sp.. Meanwhile, some special genera such as Bacillus sp., Hydrogenophaga sp. and Rhizobium sp. with functionality of iron-reducing and denitrification were found in this study, which may have a potential effect on the capture and storage of CO2 . In addition, the Shannon index decreased from 5.3302 to 1.9465 after injection of CO2 , suggesting that the biodiversity reduced significantly. Function and main metabolites analysis of bacteria in the CO2 -brine-sandstone interaction process showed that bacteria like Bacillus sp., Citrobacter sp. and Pseudomonas sp. could enhance CO2 solubility-trapping process. Bacteria metabolisms could accelerate the dissolution of feldspar and chlorites, and facilitate the formation of transition-state calcite and siderite. Otherwise, the great variation was mainly attributed to the change of condition driven by CO2 -brine-sandstone interactions, such as pH and the chemical composition of brine water(anion and cation), etc.