Tiny microbes in crude oil reservoirs that break down the fuel into heavy oil could also be used to create methane, a process that could lead to a cleaner, faster, more efficient way of extracting fuel from heavy oil deposits, according to a team of Canadian and international scientists.

Writing in the journal Nature on Wednesday, scientists from the University of Calgary and the University of Newcastle found that the bacteria that turns crude oil into the less desirable heavy oil works through a process similar to fermentation. This same process, when accelerated, also converts heavy oils into methane, they said.

It's a discovery that could revolutionize the heavy-oil industries in Canada, said University of Calgary professor Steve Larter, one of the authors of the paper.

"Because we now understand conversion of oil hydrocarbons to methane, ... this raises the exciting possibility of accelerating this process to recover energy from heavy oil fields instead of recovering the oil," Larter said in a news conference on Tuesday in advance of publication of the paper.

Heavy oil is crude oil that has biodegraded over time. It tends to be more viscous or stickier than regular crude oil, and is more difficult to extract.

"To get heavy oil out, you've basically got to melt it," Larter said. The process, he said, has been likened to "turning gold into lead," and is costly and produces greenhouse gases.

Even more difficult to extract is bitumen extracted from oilsands, for example, which require a process of injecting steam into the oilsands to heat them and thin the bitumen. The hot bitumen migrates toward the producing well, bringing it to the surface while leaving the sand in place.

Extracting the methane from the natural biodegradation process would provide a cleaner source of energy, Larter said. He said such a process could be accelerated by feeding the bacteria nutrients — or "Miracle-Gro," as he joked.

The discovery raises new possibilities for the extraction of the world's petroleum, most of which is in the form of heavy oil.

Larter said the process would be less ideal, however, for oilsands because the bacteria have already consumed more of the fuel than at a heavy-oil deposit.

"The oil that can be most easily converted is the oil that has been the least chewed on by the micro-organisms so far, so the very severely degraded oils like the oilsands bitumen aren't ideal sites for such a process."

Alberta's oilsands, the country's largest source of oil, have reserves estimated at between 1.7 trillion and 2.5 trillion barrels.

More ideal, Larter said, would be a heavy-oil deposit, such as those found in Lloydminster, Alta.

Larter said the next step would be to conduct field experiments to see whether this process can work at actual heavy oil deposits.