Denbury Resources Hopes to Use Liquid CO2 to Extract More Oil From Aging Wells

Several companies are trying enhanced oil recovery projects in North Dakota. Among them is one from Denbury Resources, which hopes to use carbon dioxide from Fallon County Montana to extract more oil from aging wells in Bowman County, North Dakota.

The project in North Dakota includes a 9.23-mile pipeline that crosses Slope and Bowman counties, and will of course require a permit from the North Dakota Public Service Commission.

A hearing for that permit has been set for 10 a.m. CST Feb. 6 at the Bowman Lodge & Convention Center, 207 West Highway 12, in Bowman. The hearing is a chance for the public to comment and share any concerns with the project.

In its permit application, Denbury said the project will provide a means to bring liquid CO2 to wells in Bowman County for tertiary oil recovery. The CO2 will be injected into the oil reservoir, where it is hoped it will not only repressurize the system, but aid in further extraction of oil and natural gas.

Denbury has been working with the Energy and Environmental Research Center for quite some time now on enhanced oil recovery using carbon dioxide at its Bell Creek field in southeastern Montana.

In 2016, EERC was given a $2.5 million grant to enhance data collection at Bell Creek. Among things EERC is interested in is whether carbon dioxide stays put once it is injected underground. There have been some who contend it won’t stay put long-term.

Enhanced oil recovery is important for the Bakken’s future economics. Present technology is leaving an estimated 90 or so percent of available oil in any given reservoir. A mere 2 to 3 percent more oil from that untapped reserve for even a couple million dollar investment would be economic.

The main use of carbon dioxide for enhanced oil recovery has so far been a tertiary method at non-Bakken sites. These include Bell Creek, which is in the Powder River Basin in Montana, and the Weyburn Field in Saskatchewan.

Denbury has been injecting a million tons of carbon dioxide annually into the Bell Creek reservoir to stimulate recovery of oil. They estimate this is going to add another 20 years of life and 40 to 50 million barrels of oil to their wells in that location.

Liquid carbon dioxide is a supercritical fluid, under 1,200 pounds per square-inch pressure. In this physical state, it will behave like a liquid for the most part. It does have some gaseous properties, but its density is greater than gas.

If studies do show that CO2 injected underground stays put, the technique could open up large underground spaces for storing carbon dioxide emissions. Weyburn, for example, could store an estimated 44 million tons of carbon dioxide.

EERC, in other studies, has determined that 80 percent of the world’s oil reservoirs could be good candidates for carbon dioxide injection. That’s potentially a vast reservoir in which to someday sequester carbon dioxide, if the science proves out. It would also give the coal industry a new commodity — carbon dioxide destined for oilfields, and, eventually, permanent storage underground.

EERC has also been testing enhanced oil recovery in Williams County in the Tioga area, as well as in the Elm Coulee Field in Montana, to determine whether carbon dioxide could enhance oil recovery in Bakken wells. The properties of Bakken wells have led researchers to think that carbon dioxide may work well here for enhanced oil recovery.

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