ReviewMicrobial dynamics in petroleum oilfields and their relationship with physiological properties of petroleum oil reservoirs

- Petroleum oilfields are resource of reduced carbon for microbial growth.
- Petroleum oil reservoirs are large geo-bioreactors, rich in wide range of anaerobic microbes.
- Petroleum oilfields possess extreme environment in terms of temperature, pressure & salinity.
- Petroleum reservoir characteristics are summarized.
- Microbial dynamics of petroleum reservoirs including origin of microorganisms is explored.

Petroleum is produced by thermal decay of buried organic material over millions of years. Petroleum oilfield ecosystems represent resource of reduced carbon which favours microbial growth. Therefore, it is obvious that many microorganisms have adapted to harsh environmental conditions of these ecosystems specifically temperature, oxygen availability and pressure. Knowledge of microorganisms present in ecosystems of petroleum oil reservoirs; their physiological and biological properties help in successful exploration of petroleum. Understanding microbiology of petroleum oilfield(s) can be used to enhance oil recovery, as microorganisms in oil reservoirs produce various metabolites viz. gases, acids, solvents, biopolymers and biosurfactants. The aim of this review is to discuss characteristics of petroleum oil reservoirs. This review also provides an updated literature on microbial ecology of these extreme ecosystems including microbial origin as well as various types of microorganisms such as methanogens; iron, nitrate and sulphate reducing bacteria, and fermentative microbes present in petroleum oilfield ecosystems.

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