GRAND FORKS (AP) - A University of North Dakota professor says research could more than double the amount of oil recovered from the Bakken shale formation in North Dakota and Montana.

A report from the U.S. Geological Survey has estimated up to 4.3 billion barrels of oil can be recovered from the Bakken in the two states using current technology.

Assistant UND Professor Zhengwen Zeng said that estimate covers only about 1 percent of the total oil in the formation. He said the Bakken's dense rock makes recovery difficult.

UND researchers have a $1 million federal grant to study the formation and look for ways to extract more oil. The research is to start in October.

Zeng said results of the research will be released over the course of the three-year project.

"Hopefully, by the end of the three years, we will have a better understanding of the stress in the Bakken Formation and be able to give better advice about how to recover more oil from it," Zeng said. "We don't understand the formation enough now to be able to produce an adequate amount of oil from it."

Ron Ness, president of the North Dakota Petroleum Council, said the more the Bakken is researched, the better. He doubts if the university's research alone will be responsible for doubling the production in the formation.

"It's all good - everybody looking at this thing is helpful and we support the university," Ness said. "But the real breakthroughs are going to come out in the field."

Eighty-one oil rigs were operating in North Dakota this week, and each costs about $50,000 daily to operate, Ness said.

"The reality is, from an industry perspective, that's $4 million a day that's going into research," Ness said.

Ness said oil companies are spending millions of dollars of their own money annually doing engineering and geologic research of the Bakken.

Ness said UND's research may be most helpful in training engineers at the school.

"We need engineers but we also need rig hands and welders," he said.

The Bakken shale formation in North Dakota holds up to 167 billion barrels of oil but only about 1 percent of it can be recovered using current technology, a recent state study says.

Zeng said increasing the Bakken's recovery rate by just 1 percent would produce more than 2 billion additional barrels of oil.