More Bakken Oil- Secondary Recovery


How much bigger can the Bakken get?


Researchers say it could get hundreds of billions of dollars bigger.


The Energy & Environmental Research Center at the University of North Dakota is working to determine if injecting carbon dioxide into the Bakken could be an effective enhanced oil recovery method.


If just 1 percent of additional oil can be recovered from the Bakken and the underlying Three Forks formation using CO2, that would equate to 1.7 billion barrels of oil, said John Harju, associate director for research for the EERC.


Assuming an average oil price of $88 a barrel, that additional 1 percent translates to $150 billion.


"The prize is big," Harju said.


Estimates show that producers will be able to recover between 2 percent and 10 percent of oil from the Bakken formation using horizontal drilling and hydraulic fracturing.


"In essence, somewhere between 90 and 98 percent of the oil in that reservoir is still there after we've gotten to the economic limit on one of these Bakken wells today," Harju said. "This is where the notion of carbon dioxide into the reservoir comes in."


CO2 injection has been used successfully to recover oil in other areas, including Canada, in what are known as conventional oil reservoirs.


The Bakken, however, is unconventional. That is, the rock has low porosity (very few holes in the rock) and low permeability (the holes that are there are isolated), so moving the oil is more difficult.


Other areas have successfully used water flooding as a secondary oil recovery method before using CO2 injection.


"We don't believe, at least on a widespread scale, that water flooding will be an effective technology," Harju said. "It may be in sporadic portions of the basin."


Harju said he knows of two field tests of CO2 injection into Bakken rocks - one in Mountrail County and one in Montana. Neither was economically successful, but they will help researchers with their laboratory experiments.


"They were illustrative of the challenge," Harju said.


The EERC's partners include the U.S. Department of Energy, the North Dakota Industrial Commission Oil and Gas Research Council and companies TAQA North and Marathon Oil Co.


Scientists don't have time on their side.


For CO2 injection to work, the pressure in the oil reservoirs can't get depleted too much before the gas is injected, Harju said.


"Because of the peculiar and unique nature of these rocks and the gargantuan size of the resource, the timelines are going to be diminished greatly," Harju said. "Things that took us 20, 30, 40 years to arrive at previously, we need to do in two and three and four years now.


If the method is proven to be a viable option for the Bakken, the next challenge is securing CO2.


The main source for CO2 in North Dakota is the Dakota Gasification Co.'s Great Plains Synfuels Plant in Beulah, N.D. But the plant already transports CO2 to Canada via a 205-mile pipeline for enhanced oil recovery.


The pipeline has taps on it that could potentially be used for to provide CO2 to the Bakken, spokesman Daryl Hill said.

"If a market would develop an

d if there was a need for it, we'd certainly be willing to look at being a part of providing that," Hill said.


Meanwhile, Denbury Resources is working on CO2 enhanced oil recovery in Montana and Wyoming in conventional oil reservoirs. The company is building a CO2 pipeline that will extend to the Cedar Creek Anticline in southeastern Montana, Denbury spokesman Ernesto Alegria said.


In the future, the pipeline could potentially be extended to the Bakken, Alegria said.


"We will have plenty of CO2 from our Riley Ridge facility - if that day ever came," he said.


Harju said he doesn't know yet how much CO2 would be needed if the method could be used successfully in the Bakken.


Currently, 2 billion cubic feet per day of CO2 is injected in the Permian Basin in western Texas, Harju said.


"This could be that big, maybe even bigger," Harju said.


Harju said researchers hope to be in the field with this project within two years. He expects to publish some early results for the Williston Basin Petroleum Conference in Regina, Saskatchewan, next spring.


The potential economic impact of enhanced oil recovery is huge, Harju said, with the state benefiting through its oil extraction and production taxes.


"This project is really focused on developing all of that fundamental understanding that allows us to utilize CO2 effectively and maybe move that recovery percentage a percent or 2 or 3 or 5," Harju said. "With each of those percents, we start talking about numbers bigger than $100 billion in terms of value."