Optimized Oil Recovery

A partnership of research and industry is developing a strategy to use the carbon dioxide from coal power emissions to recover more oil from North Dakota’s oilfields without drilling new wells

BY LISA GIBSON

Carbon dioxide is one of those “funny molecules” that can change the properties of oil in the ground and facilitate its flow to extraction wells, says Charles Gorecki, director of subsurface research and development at the University of North Dakota’s Energy & Environmental Research Center in Grand Forks.

Those property-altering components of CO2 have been used in enhanced oil recovery projects on small and demonstration scales — and even one Montana-based commercial-scale project — in our region for years. Progress on the concept has been made through the Plains CO2 Reduction Partnership (PCOR), funded by the U.S. Department of Energy and more than 100 of the EERC’s public and private program partners. Traditionally, CO2 used in PCOR injection projects comes from natural gas processing, but the partnership — including the EERC, the Lignite Energy Council, the North Dakota Petroleum Council, and many others — now is working to make coal-fired power plants the next supplier. That would reduce coal plant stack emissions while aiding in extracting up to 20 percent more of the oil that sits beneath the ground in western North Dakota.

In our region, and particularly in North Dakota, the oil and gas industry is one of the main users of the predominantly coal-fired power, says John Harju, vice president for strategic partnerships for the EERC. “You’ve got coal-fired energy serving this extractive industry of oil and gas,” he says. “Geologically, we have the opportunity of these prolific oil and gas basins to sequester carbon dioxide.”

It works like this: The CO2 is captured from the coal-fired power plants, separated from the other components in the stack and compressed into what’s called supercritical fluid. Supercritical CO2 is then moved to the oilfields and pumped into reservoirs to allow its oil-altering properties to get to work on enhancing the flow to the existing wells. That increases the amount of oil recovered, without drilling new wells, and, over time, sequesters that carbon in the subsurface.

Transforming the CO2 into supercritical fluid allows large masses of CO2 to be moved in relatively small volumes, Harju says. While some will come back out with the pumped oil, it is injected back in and reused repeatedly until it stays stored underground. “All of the CO2 we bring to the field is ultimately stored in the reservoir,” he says. “It’s just that we might use it three, four, five, six times.”

From the Source

Coal-fired power plants produce up to 30 million tons of CO2 each per year,

Harju says, making them a great source for the enhanced oil recovery project.

“At the Lignite Energy Council, one of our goals is to look at how we can reduce the carbon dioxide from making use of lignite,” says Mike Jones, vice president of research and development for the Lignite Energy Council. “We see this as an opportunity to produce a low-cost electricity source and, at the same time, have a source of carbon dioxide that can be enhancing the output from the oilfields in western North Dakota.”

Carbon capture is generally done with solvents, a liquid applied to the emissions stream that easily absorbs CO2 only, leaving behind other elements such as nitrogen and water vapor, Harju says. That solvent containing CO2 is then heated to drive off the CO2 , which is then compressed and ready for use. Heating the solvent consumes large amounts of energy so some research will focus on how to transfer energy from the existing power plant boilers or how to produce a solvent that is already hot enough to liberate the CO2 , Harju says.

“The last thing we want to do is expend a bunch of energy incorporating carbon capture because then you kind of defeat the purpose,” says Mike Holmes, director of energy systems development for the EERC. The whole idea is to capture, compress and inject the CO2 in a manner optimized for cost, efficiency and effectiveness, he says.

The EERC and the Lignite Energy Council also are researching a process called the Allam Cycle, which gasifies coal instead of combusting it. That produces a syngas of carbon monoxide and hydrogen that can be burned in oxygen at high pressures to create a pure stream of water and CO2, Jones says. The syngas also can be used to turn the power-production turbines, instead of using steam released from combusting coal.

If coal emissions can be lowered and oil production enhanced in one project at a reasonable cost, both industries will have responded to changing environmental regulations while allowing for more business activity in the western part of North Dakota, Jones adds. “A lot more oil could be produced and all the economic benefits that come with that,” he says. “As the Lignite Energy Council, of course we’re interested in what we can find that allows lignite to continue to participate as a key opportunity for energy in this state and region.”

Scaling Up

Next, the process needs to be built out to commercial scale so it can make an impact on entire industries and the country. “These are very, very big capture systems that we’re building out,” Harju says. “It’s different than applying it on a small scale.”

Harju says building to a large scale means figuring out a few things: the appropriate size for modules to replicate the small-scale research; what other elements — such as particulate matter — might exist in coal-fired emissions that also will need to be removed, separately from the CO2 ; and what exactly happens to the CO2 within the reservoirs.

The total value of the work behind all PCOR projects thus far — including those with and without injection components — is well in excess of

$100 million and in the coming years will be in the billions of dollars, Harju says. PCOR began in 2003 and is scheduled to wrap up at the end of 2018. It’s initial goal was to store 1 million tons of CO2, but it has succeeded in storing triple that, Gorecki says. The partnership is one of seven across the country started by the DOE, six of which remain.

PCOR is an enormous project that spans North Dakota, South Dakota, Montana, Wyoming, Iowa, Minnesota, Wisconsin, Nebraska, Missouri and the Canadian provinces of Manitoba, British Columbia, Alberta and Saskatchewan. But “North Dakota represents one of the best opportunities to use carbon dioxide for enhanced oil recovery and also to store large volumes because we have this great juxtaposition of coal resources and coal-powered facilities that are all close to the oil and gas operations,” Gorecki says. “We have industries — both oil and gas and the power industry — that are engaged and want to make meaningful strides.” Despite low oil prices, oil extraction will continue to use an immense amount of power, doubling or tripling current use, Gorecki says, adding the current downturn will not last forever.

“Great partners make great projects and we are just absolutely blessed with many, many, many great partners in this work,” Harju says. “Without all of them collectively working toward this common goal, we wouldn’t be able to make the kind of progress we’re making.” PB

Lisa Gibson Editor, Prairie Business 701.787.6753

lgibson@prairiebusinessmagazine.com