Microbial Communities Affected by Hydraulic Fracturing and Environmental Factors within an In Situ Coal Reservoir

Area of Science:

• * Geomicrobiology and Reservoir Engineering
• * Microbial Ecology of Subsurface Environments

Background:

• * Coalbed methane (CBM) bioengineering utilizes microbial action for carbon dioxide conversion and utilization within the carbon cycle.
• * Underground coal reservoirs host complex microbial communities shaped by their environment.
• * Laboratory studies on reservoir microorganisms do not fully replicate in-situ conditions and interactions.

Purpose of the Study:

• * To analyze the microbial response in coal reservoirs following hydraulic fracturing.
• * To understand how hydraulic fracturing impacts microbial community structure and function in situ.
• * To investigate the role of hydraulic fracturing in enhancing microbially enhanced coalbed methane (MECBM) production.

Main Methods:

• * Application of 16S rRNA sequencing technique.
• * Analysis of coalbed methane production water samples from hydraulically fractured wells in the Qinshui Basin.
• * Comparison of microbial communities in fractured versus non-fractured wells.

Main Results:

• * Hydraulic fracturing significantly improved the diversity of microbial communities involved in organic degradation.
• * A notable increase in the abundance of Actinobacteria, Aminicenantes, and Planctomycetes was observed post-fracturing.
• * Methanogen diversity and abundance, particularly in fractured wells, were influenced by ecological factors, affecting metabolic pathways.
• * The impact of hydraulic fracturing on microbial communities was observed to persist for several months.

Conclusions:

• * Hydraulic fracturing positively influences microbial communities in coal reservoirs, enhancing organic degradation and carbon cycling.
• * The observed microbial shifts strengthen methane and carbon dioxide circulation, supporting MECBM.
• * This study provides a theoretical foundation for optimizing microbially enhanced coalbed methane recovery through hydraulic fracturing.