Discovery of Mechanism of Biodegradation of Crude Oil to Methane Could Lead to Cleaner Oil-Sands Production and Enhanced Energy Recovery from Oilfields
14 December 2007
An international team of researchers has shown how anaerobic microbes in oil deposits around the world—including in unconventional sources such as the oil sands—naturally break down crude oil into methane in the reservoir.
Their discovery—published in the journal Nature—could lead to more energy-efficient, economic ways to extract difficult-to-recover energy from oilfields or heavy oil and oil-sands deposits.
Biodegradation of crude oil into heavy oil in petroleum reservoirs is a problem worldwide for the petroleum industry. The natural process, caused by bacteria that consume the oil, makes the oil viscous and contaminates it with pollutants such as sulfur. This makes recovering and refining heavy oil difficult and costly.
Some studies have attributed the biodegradation to aerobic bacteria, stimulated by the surface recharge of oxygen-bearing waters. This hypothesis has been supported empirically by the likelihood of finding biodegrade oils at higher levels of degradation near the surface.
More recent findings, however, suggested that anaerobic processes dominate in the subsurface environment, despite slow reaction kinetics and uncertainty as to the actual degradation pathways.
The team of researchers, including scientists from the University of Calgary (Canada), the University of Newcastle (UK) and Norsk Hydro Oil & Energy in Norway, report in Nature that the dominant process is, in fact, fermentation by anaerobic methanogenic bacteria that live in oil reservoirs.
Their data suggests a common methanogenic biodegradation mechanism in subsurface degraded oil reservoirs which results in consistent patterns of hydrocarbon alteration and the common association of dry gas with severely degraded oils observed worldwide.
This is the main process that’s occurring all over the Earth, in any oil reservoir where you’ve got biodegradation.
—Steve Larter, University of Calgary
Using a combination of microbiological studies, laboratory experiments and oilfield case studies, the team demonstrated the anaerobic degradation of hydrocarbons to produce methane. The findings offer the potential of feeding the microbes and rapidly accelerating the breaking down of the oil into methane.
Instead of 10 million years, we want to do it 10 years. We think it’s possible. We can do it in the laboratory. The question is: can we do it in a reservoir?
—Steve Larter
Doing so would transform the heavy oil/oil sands industry, which now manages to recover only about 17% of a resource that consists of six trillion barrels worldwide. Oil sands companies would be able to recover only the clean-burning natural gas, leaving the hard-to-handle bitumen and contaminants deep underground.
Understanding biodegradation also provides an immediate tool for predicting where the less-biodegraded oil is located in reservoirs, enabling companies to increase recovery by targeting higher-quality oil.
It gives us a better understanding of why the fluid properties are varying within the reservoir. That will help us with thermal recovery processes such as SAGD (steam-assisted gravity drainage).
—Steve Larter
The research team also discovered an intermediate step in the biodegradation process involving a separate family of microbes that produce carbon dioxide and hydrogen from partly degraded oil, prior to it being turned into methane. This paves the way for using the microbes to capture this CO2 as methane, which could then be recycled as fuel in a closed-loop energy system. This would keep the CO2 out of the atmosphere.
The petroleum industry already has expressed interest in trying to accelerate biodegradation in a reservoir, according to the researchers. Field tests may begin by 2009.
Resources
D. M. Jones, I. M. Head, N. D. Gray, J. J. Adams, A. K. Rowan, C. M. Aitken, B. Bennett, H. Huang, A. Brown, B. F. J. Bowler, T. Oldenburg, M. Erdmann & S. R. Larter; “Crude-oil biodegradation via methanogenesis in subsurface petroleum reservoirs”; Nature, Published online 12 December 2007 doi: 10.1038/nature06484
Life exists everywhere on this planet, even thousands of feet underground.
Combine this with Toe Heel Air Injection (THAI) that can supposedly recover 70-80% of the heavy oil in a reservoir, and I wonder what oil and natural gas supplies will do over the longer term. THAI might have the potential to at least slow the downslope and buy us some time.
Posted by: Cervus | 14 December 2007 at 06:23 PM
@Cervus:
Good comment.
Additionally, I think it is ironic, that while the oil companies are scrambling to squeeze oil from sand, the auto companies are bringing out their latest super, fuel-eating, ICE-powered hot rods and Hummers.
The auto-makers continue to produce PR built around outdated thinking that 16-20mpg is good fuel mileage and the public keeps buying the cars when they should be insisting on electric drive lines and at least 40mpg. Let's hope the companies will soon get to work mass-producing high-mileage autos.
Posted by: Lad | 14 December 2007 at 07:39 PM
I would have thought that producing biogas from agricultural waste streams on the surface would be cheaper than extracting oil sands in the form of gas, but apparently, not so. Meanwhile, China and India are gung-ho about huge methane hydrate deposits recently discovered in their territories. The fossil fuels industry has a hard time dealing with the concept of energy that didn't come out of a hole in the ground.
Whatever the source, one thing does seem clear: the oil age won't come an end for the lack of oil. It'll be because of the abundance of cheaper fossil and renewable gas. I suspect we'll hear a lot more about natural gas vehicles in coming years, especially in the emerging economies. People figure out ways to use whatever energy source is cheapest. However, he high cost of compressors and on-board tanks limit the market potential of CNG. Liquefaction via F-T liquids or DME is also very expensive.
Fortunately, there are other ways to leverage natural gas for transportation, e.g. adsorbed NG dispensed at pipeline pressure (~35 bar). Buses, trucks and delivery fleets are prime candidates, replacing efficient but dirty diesels. Passenger car applications will depend on figuring out how the heavy absorption material can do double duty as soundproofing without compromising crash safety.
An intermediate application may be large cars that are can be operated as sharecabs on a regular driver's license. This form of transportation is popular in Turkey (dolmus taxis), South Africa, Philippines (jitneys) and many other places many are still too poor to own a motor vehicle of their own. These services also represent jobs, reduce congestion and achieve excellent fuel economy per passenger-mile.
Another option for using gas - along with other energy sources - to support transportation is of course electric vehicles. Congestion, traffic safety and air quality are all are appalling in the mega-cities of the developing world. Overhead wires would give traffic planners a technical excuse for dedicating lanes on motorways and urban thoroughfares to tall vehicles, i.e. buses and trucks, equipped with (retractable) connectors for live and ground. Electrical ground could also be presented as a metal rail in the road. Ideally, these vehicles would also feature a small on-board genset to ensure they can access off-grid locations.
The hard issue is making sure only authorized vehicles can connect to such a grid, which may need stationary electricity buffers (e.g. banks of superflywheels) just to maintain voltage in a tolerance band. These would double as shared recuperators.
Posted by: Rafael Seidl | 14 December 2007 at 11:52 PM
This is good news, even the methane hydrate deposit in India and China. But if that methane end up used in IC engines, we are not gaining much in terms of GHG.
We need someone to come up with a practical methane fuel cell.
Posted by: SM | 15 December 2007 at 07:34 AM
SM,
They are called SOFC and MCFC. A PEM with a reformer could also work, as it could make hot water and H2 for electricity. I believe Honda is working on one (home refueling station) for its fuel cell vehicles.
Posted by: allen_xl_z | 15 December 2007 at 08:16 AM
NG offers more flexibility than liquid fuels as well.
Burn it directly either for transportation (cleaner than liquid fuels), or use it in higher-efficiency applications than vehicles (e.g. 90% efficient condensing furnace for space heat)
Or reform it for fuel cell use for transportation or for Honda's home refueling station (power and hot water cogeneration).
Posted by: Bill | 15 December 2007 at 08:38 AM
This is not good news. More fossil fuel means more co2. That means more co2 in the air and sea. Say goodbye to coral reefs, lobsters and clams and all the other life that depends upon calcium carbonate.
Posted by: domenick | 15 December 2007 at 12:22 PM
Some more amazing technology from the fossil fuel industry -Matches-tm, Ingenious.
Certain advisors to the mining industry and govt's have in place scenarios where CO2 is allowed to run out to over 1000 ppm or 3 times the desirable upper limit.
While it is obvious that the demand for these fossil fuels will continue to rise, It should also be obvious that this is not going to be managable.
Still as long as here is a dollar in fossil fuel energy
people will seek profit over reason.
Keep digging our hole thank you.
Posted by: Arnold | 15 December 2007 at 04:05 PM
This at least gives the West a prospect of salvation from rapid decline of both oil and natural gas supplies. Many oil fields which are played out even with today's best recovery technology could produce gas for some time (oil fields first produced with 19th-century methods may have large amounts of recoverable oil left in them). If this can come on-line quickly, the fast-crash scenarios no longer look tenable.
Posted by: Engineer-Poet | 15 December 2007 at 06:01 PM
This is fermentation, disproportionating carbohydrate to methane and CO2: 2 "CH2O" -> CH4 + CO2. Note that half the available carbon ends up as CO2 right from the start, so keep that in mind when you do your energy calculations.
Posted by: dt | 16 December 2007 at 12:56 PM
Well there never was the prospect of running out of hydrocarbon fuels.
The issue was always going to be that we'd find some other way to get our hydrocarbons.
Which of course would mean that oil production would merely get dirtier.
_
Kind of disturbing when people put Peak Oil ahead of Global Warming.
Posted by: GreyFlcn | 16 December 2007 at 02:00 PM
GreyFalcon:
If the world economy goes into collapse because oil shoots up to $400 a barrel, with worldwide shortages, there will be no money to invest in low/no carbon energy. Nobody's going to care about global warming if they don't have jobs and can't put food on the table. And if even a few of the dire predictions from the peak oil doomers come true, then we're all screwed anyway. I suppose that's one way to reduce CO2 emissions, but I'd rather avoid it.
This and THAI give us some breathing room so we can focus on climate change.
Posted by: Cervus | 17 December 2007 at 05:44 PM
I'd hardly call doubling our greenhouse emissions from oil production "focusing on climate change".
Posted by: GreyFlcn | 18 December 2007 at 12:47 AM
Oil sands companies would be able to recover only the clean-burning natural gas, leaving the hard-to-handle bitumen and contaminants deep underground.
Strange idea, seeing that oil sands companies currently burn lots of low-value methane to convert bitumen into high-value synthetic crude oil.
Posted by: doggydogworld | 18 December 2007 at 11:23 AM
If worldwide fossil fuel consumption doubles every 10 - 15 years, how long will the extra reserves last?
Will pollution + GHG also double in the same time period? If so, where will ecology and climate change be after another 50 years of ever increasing fossil fuel consumption?
Posted by: Harvey D | 19 December 2007 at 09:58 AM