Microbially Enhanced Oil Recovery (MEOR) is the use of microbes in petroleum reservoirs to enhance the amount of oil that can be produced.
The microbes in MEOR are typically hydrocarbon-utilising, non-pathogenic micro-organisms that are naturally found in petroleum reservoirs or are introduced.
As a result of their metabolic activity, the microbes excrete natural and non-toxic bio-products such as alcohols, gases, acids, surfactants and polymers.
These can cause a series of very desirable changes in the physical-chemical properties of the crude.
There is also a marked improvement or a near-complete restoration of the lithological properties of the reservoir rock.
Improving production of Australia’s oilfields
Demand for fossil fuels approaches or even outstrips supply growth.
Despite advances in renewable energy sources and the likely move to a hydrogen economy, oil will remain a key energy source for 20-30 years.
However, globally it’s recognised that it is getting progressively harder to find more oil. Most likely, the majority of the oil provinces and giant oilfields have already been discovered.
The best way to influence oil production and hence Australia’s balance of payments is by improving productivity of known oilfields. Future oil exploration is focussing more and more on difficult targets.
The best way to influence oil production and hence Australia’s balance of payments is by improving productivity of known oilfields.
In 2003 Australia was 75 per cent self-sufficient in oil, but this is predicted to decline to 50 per cent by 2015.
This will contribute to an ever-widening trade deficit.
In mature basins a major component of the addition to reserves is derived from 'reserve growth' (field 'growth'). While finding and exploiting more subtle traps and oil pools in or near existing oil fields is important, as is exploring for oil in new petroleum provinces, Enhanced Oil Recovery (EOR), sometimes called Improved Oil Recovery (IOR) or tertiary oil recovery, will play a critical role in sustaining oil supply from mature fields.
Primary recovery usually only accesses 30 to 35 per cent of the original oil in place (OOIP).
Secondary and tertiary recovery methods may net a further 15 to 25 per cent OOIP, leaving 30 to 55 per cent OOIP left behind as irrecoverable or irreducible oil in the reservoir.
MEOR technology targets this remaining oil and aims to enable production of 80 to 85 per cent of OOIP.
While it is clear that biocatalysis performed by microbes may promote beneficial chemical reactions such as the production of biosurfactants in a very specific and energy-efficient manner, a sound understanding of the underlying principles is important to predict site-specific effects of microbial activity on fluid flow in porous media and hence on the efficiency of oil production.