Microbial Community Composition and Function in Jiangsu Oil Reservoir Cores, China

Area of Science:

• Geomicrobiology
• Petroleum Geoscience
• Biogeochemistry

Background:

• Shale oil reservoirs present extreme conditions: high temperatures, limited nutrients, and confined spaces.
• Understanding microbial roles is key to biogeochemical cycles and origins of life, but community composition and function are poorly understood.

Purpose of the Study:

• To investigate the microbial community structure and metabolic functions within shale oil reservoirs.
• To identify microorganisms capable of hydrocarbon degradation and their role in subsurface biogeochemical cycling.

Main Methods:

• Analysis of shale core samples using X-ray fluorescence, powder X-ray diffraction, and scanning electron microscopy.
• Crude oil fractionation and characterization of hydrocarbon content (C11-C35 n-alkanes).
• Metagenomic analysis to identify microbial communities and functional genes.

Main Results:

• Shale samples contained transition metals, clay minerals, and significant porosity.
• Hydrocarbon-degrading bacteria (Marinobacter, Alcanivorax, Alkanindiges, Nocardioides) were identified.
• Metagenomic data revealed genes for aerobic hydrocarbon degradation, denitrification, and direct nutrient assimilation (DNRA) in the HY7 sample.

Conclusions:

• Microbial communities in shale oil reservoirs are metabolically active, utilizing crude oil components.
• These microorganisms play a role in subsurface carbon and nitrogen cycling.
• Findings provide insights for potential in situ microbial applications in shale oil reservoir development.