BISMARCK, N.D. _ If promising tests results from the lab can be duplicated in the field, they could lead to the recovery of more oil from Bakken wells, a North Dakota researcher says.
Steven Hawthorne, a senior research manager for the Energy and Environmental Research Center in Grand Forks, spoke Wednesday at the Williston Basin Petroleum Conference about enhanced recovery.
Between 4 percent and 6 percent of oil is now recoverable from the Williston Basin, Hawthorne said. Another 1 percent could be “a big game on this field,” he said.
He estimated that 1 percent would equal an additional 2 billion to 9 billion recoverable barrels of oil.
In lab experiments, Hawthorne said, using carbon dioxide on small samples of rock produced high recovery rates, depending on the pressure and duration with which it is applied to the rock. In the lab, he said, the recovery can reach as high as
90 percent in some cases.
“CO2 and associated gasses are capable of mobilizing oil from upper, middle and lower Bakken,” Hawthorne said. “But we need to work on increasing the rate of the recovery process.”
The technology is currently available to capture CO2 but it’s too costly, he said. The ability to harness enough of the gas to use it on a scale to recover the additional billions of barrels of oil also isn’t yet available.
The U.S. Geological Survey in spring 2013 updated its estimate of recoverable oil from the Williston Basin to between 4.4 billion and 11.4 billion barrels, averaging 7.4 billion barrels using current technology. The 7.4 billion figure approximately doubles the previous estimate.
Hawthorne said conventional vertical wells average between 15 percent and 20 percent recovery. Enhanced oil recovery processes can produce up to another 15-20 percent in conventional wells, he said.
But tight shale rock in the Williston Basin and the fact that many wells reach approximately 10,000 feet and are drilled horizontally make enhanced oil recovery more difficult than in conventional wells, Hawthorne said.