If the ill-informed hysteria surrounding the safety of fracking is anything to go by, I can imagine the headline above being used to describe a highly promising microbial enhanced oil recovery (MEOR) technique.
In 2014 the UK witnessed the farcical situation where Vivienne Westwood, a fashion designer, was an expert in drilling and well completion practices in Wyoming and Delaware, and knew more about lithology than the British Geological Society.
If the same anti-fracking mindset persists the use of bacteria for oil recovery could witness similar ill-informed public and press outrage.
The MEOR technique in question involves using bacteria to convert irrecoverable oil into methane (Natural Gas) and subsequently producing the bio-synthesised gas.
Oilfield Waterflood
Production is greatly enhanced from oil fields using waterflooding. This is common practice and involves injecting seawater into the oil bearing rock.
This prevents the pressure in the oilfield from dropping and sweeps oil towards the production wells.
Without waterflood oil recovery levels would be around 10 – 20% of the oil in place; with waterflood this will increase to 60-70%.
The water cannot sweep out oil contained within some parts of the rock, hence when an oilfield is decommissioned the oil company is leaving around one third of the oil behind.
Microbial Enhanced Oil Recovery – MEOR
Because of the large amount of oil left behind post waterflood, oil companies have for many years researched a range of enhanced oil recovery techniques, including the use of polymers, surfactants, adding heat and injecting high pressure gas.
These techniques are expensive and, apart from the thermal methods, their use has been limited.
But there are a range of MEOR options under development with one in particular showing much promise: the use of methanogens.
Methanogens are present in the gut of ruminants and in wetlands; they are responsible for the methane emitted in cow farts and for Marsh Gas (methane).
For methanogens to thrive they require a biomass (grass in the cow’s gut) or oil remaining in rock post waterflood.
The MEOR methanogen option is to inoculate the waterflood with methanogens and nutrients prior to cessation of oil production.
The methanogens subsequently colonise the oilfield and metabolise the trapped oil, converting it to methane.
The bio-produced methane gas is much more mobile than the trapped oil and migrates upwards, accumulating as a large gas cap.
The gas cap is then produced through the existing oilfield wells and processing facility.
It could be a low cost, highly effective hydrocarbon EOR recovery option for a mature province like the UK. So where is the catch?
Whilst methanogens function at 38.6 degrees Celsius and atmospheric pressure (the same as you’d find in a cow’s gut), developing a methanogen capable of metabolising trapped oil at the subsurface conditions of 80 – 120 0C and at many hundreds of atmospheres will be difficult.
It will require straining and probably genetic modification of the existing methanogen community – the Frankenstein Bug.
For those understandably concerned about any process which produces more fossil fuel, the synthesized methane need not be used as a fuel source.
It could be reformed into Syngas – hydrogen and carbon monoxide – with the hydrogen used as carbon free fuel and the carbon monoxide used as a feedstock for the manufacture of Carbonyls, Methanol and Formaldehyde.
Methanogen EOR research
Whilst there is EOR methanogen research activity in other parts of the world the UK appears to have no active groupings. This is surprising since the technology sits extremely well with the Oil and Gas Authority’s (OGA) primary remit of maximising economic recovery from the UK’s remaining hydrocarbon reserves.
Indeed the OGA’s EOR Strategy Document makes no mention of Microbial EOR. Low salinity waterflood, which reduces the oil-rock adhering forces, is highlighted as a preferred technique.
This is somewhat baffling as it is a high cost option not suited to mature provinces.
MEOR will also prolong field life, defer decommissioning and further preserve the UK’s oil and gas infrastructure – key objectives of the OGA. Furthermore, the UK’s renowned expertise in biotechnology makes the lack of UK MEOR activity even more strange. MEOR in the UK – where are you?
Tom Baxter is a senior lecturer in chemical engineering at Aberdeen University
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