Hydrocarbon Degradation in Petroleum Reservoirs

In-reservoir petroleum biodegradation has resulted in vast deposits of heavy oil around the globe. Extraction of heavy oil is more costly and less efficient than conventional oil production and consequently oil biodegradation on geological timescales has significant economic and environmental impacts. The processes that have led to the biodegradation of oil in situ have only recently begun to be elucidated and we have at best a qualitative understanding of the factors that promote oil biodegradation in petroleum reservoirs. A synthesis of current thinking on the mechanisms of, and controls on, in-reservoir oil biodegradation is presented. This is placed in the context of oil-field microbiology and used to identify potentially fruitful avenues of research required to fill some of the gaps in our knowledge.