Solvent bitumen extraction methods take the steam out of oilsands development
Several waterless extraction methods being piloted that use less energy, produce fewer emissions
EDMONTON—Oilsands producers have been under siege for years, with environmentalists, politicians and even aging rock stars criticizing their environmental performance for greenhouse gas (GHG) emissions and vast water use.
But if oilsands companies could eliminate the use of water completely it would truly be a “game-changer,” says Les Little, executive director of energy technologies for Alberta Innovates Energy and Environmental Studies (AI-EES), the lead agency for energy and environmental research in Alberta.
Right now, steam assisted gravity drainage (SAGD) and cyclic steam stimulation (CSS) are the methods used most to coax the tar-like bitumen out of the ground.
But producers are investigating alternative methods of extracting bitumen using solvents instead of steam, which could lead to multiple environmental benefits.
“With the use of solvents, producers can displace steam, which leads not only to reducing water use, but to much lower greenhouse gas emissions,” says Little, who has been involved in oilsands research for more than 30 years.
He says the problem with current steam-based technologies is the need for incredibly high temperatures to vaporize the water.
Achieving those temperatures—some as high as 200°C—means burning a lot of natural gas.
While there have been laboratory experiments for decades investigating the use of solvents as a thinning agent to get bitumen flowing without using steam, there are now promising technologies that have advanced to the pilot plant stage.
Later this year CSS and SAGD pioneer Imperial Oil Ltd. will after 20 years of trials start field-testing a cyclic solvent process (CSP) at its Cold Lake project site in northeastern Alberta.
Imperial spokesperson Pius Rolheiser says the firm is eager to see its CSP approach work “because it would virtually eliminate water use and reduce our overall GHG emissions by 90 per cent.”
Currently, the energy giant needs 3.6 barrels of water for every barrel of bitumen it produces at its Cold Lake site, where it pumps out about 200,000 barrels of oil each day.
That works out to more than 114 million litres of water for every 31.8 million litres of oil.
Now Imperial plans to use a propane-butane mixture as its solvent at the horizontal well pilot plant near the Saskatchewan border.
The $100-million project was partially funded by the Alberta government, including $10-million from the not-for-profit Climate Change and Emissions Management Corporation (CCEMC).
According to Little of AI-EES, solvents such as propane, butane and pentane could substantially cut GHG emissions.
“Solvents can dissolve in bitumen, reducing the viscosity of the bitumen, making it easier to transport by pipeline and easier to upgrade and refine,” he adds.
Prof. Hashem Salari, a research associate at the University of Calgary’s Solvent Heat Assisted Recovery Processes (SHARP) research consortium agrees, saying it is vital for the industry to move away from traditional steam-based technologies.
He says 14 companies support the initiative, which has been exploring solvent-based technologies since 2008.
“They realize they have to reduce their environmental footprint,” he says. “But solvents are expensive, so we’re looking at hybrid systems, where you also introduce some heat into the reservoir, which helps to reduce the viscosity of the bitumen much faster.”
Additionally, if some steam is used then it’s easier to separate the solvents from the bitumen, which allows the solvents to be recycled for subsequent use.
Salari says the school’s lab has tested bitumen from various producers, using various solvents with each, and is convinced solvent-based processes will be used throughout the industry in a few years.
Another firm pushing ahead in investigating solvent extraction technologies is Suncor Energy Inc.
The company is currently involved in a pair of CCEMC-funded projects using solvent-assisted processing at two pilot plants.
The first, N-Solv Corp.’s bitumen extraction solvent technology (BEST) pilot plant, is built on a 300-metre well-pair and surface processing plant at Suncor’s Dover oilsands lease about 50 kilometres northeast of Fort McMurray, Alta.
The pilot consists of seven observation wells, one well pair—a solvent injector and an oil producer—and surface facilities for oil and solvent separation.
Alexander Stickler, vice-president of business operations for Calgary-based N-Solv, says the technology uses butane heated to about 60°C and converted into a solvent vapour.
The vapour condenses in the reservoir much like steam droplets in a steam bath, reducing the viscosity of the bitumen.
Stickler says the injection at the plant will start soon and is expected to produce 300 to 400 barrels a day at some point in late 2014.
The N-Solv technology, first experimented with by company founder John Nenninger in the 1970s, is expected to reduce capital costs for oilsands developers since the plants take up less space than SAGD projects, produce higher quality oil and substantially reduce environmental impacts overall, Stickler adds.
In addition to the reduction in on-site GHG emissions of about 85 per cent, overall emissions are cut by 50 per cent, he notes.
And, because the viscosity of the bitumen is raised from about eight American Petroleum Institute (API) gravity to 13 API gravity, coke and other heavy contents of the bitumen are left behind in the reservoir, meaning less diluent is needed.
Not having to store coke, for which there are few markets, also yields financial savings and GHG reductions, Stickler says.
The project received $10-million from the CCEMC toward its total capital cost of about $56-million.
The second project, the enhanced solvent extraction incorporating electrocmagnetic heating (ESEIEH) technology, also uses a pilot plant at Suncor’s Dover site, where testing should also begin in late 2014.
Backed by a consortium of Suncor, Devon Energy Corp., Nexen Inc. and the Harris Corp., the project combines radio waves with solvents using technology developed by Florida-based Harris Corp.
The electromagnetic heating concept works in a similar way to a microwave oven, but uses lower-frequency radio waves.
Radio frequency emitters in wellbores generate electromagnetic waves that produce heat as they energize molecules in the reservoir.
Once the reservoir is hot, a solvent is injected.
“The solvent helps the bitumen loosen up,” says Kelli Stevens, spokesperson for Suncor. “It helps get the bitumen dripping off the sand at a lower temperature.”
Stevens says the process is estimated to reduce overall GHG emissions by 80 per cent and produce a lighter bitumen.
“We’re hoping that ESEIEH can improve efficiency, therefore reducing or eliminating water consumption,” she explains. “It’s good for the environment and it’s also good for us socially because water is a big concern for our stakeholders. So the less water we can use, the better.”
Stevens says if the project works as expected, GHG reductions will come in two ways: First, by removing steam from in-situ recovery; and second, by reducing energy requirements.
She says removing steam from the in-situ process eliminates the need to burn fossil fuels to heat water, resulting in decreased emissions.
Because it takes less energy to use a solvent combined with electromagnetic heating to mobilize the bitumen at lower temperatures, energy requirements are also reduced.
The key questions to be answered with the pilot is how long will it take to heat the reservoir and how much electricity will be required to produce a barrel of bitumen.
The CCEMC contributed $16.5-million to the project, which involves an investment of $33-million.
AI-EESI’s Little says the three technologies vary, but the overriding theme is that Imperial’s CSP approach “uses time,” while the other two approaches try to stimulate the reservoirs more rapidly.
“The CSP approach is using a cyclic soaking approach, allowing more time for the solvent to work,” he said.
He says there are dozens of other solvent-related approaches now at various stages of development, but it’s not a “one size fits all” equation.
“It will take a suite of technologies and all have costs associated with them,” he explains. “For instance, all of the solvents are hydrocarbon based and there’s a cost associated with them.”
However, Little says the oilsands industry must improve its environmental track record or risk losing its “social licence to operate.”
And with game-changing research well underway, that social licence may be renewed after all.
—With files from Rebecca Reid