Bloomberg News

OPEC has formed a committee to examine the impact of U.S. shale oil, an admission that the burgeoning supply is worrying some of its members.

“It is a concern,” Nigeria’s Petroleum Minister Diezani Alison-Madueke said after the Organization of Petroleum Exporting Countries decided to keep its production target unchanged at a meeting on Friday. The committee will consider the effect of shale oil on the global market for OPEC crude, she said.

U.S. mastery of hydraulic fracturing and horizontal drilling techniques has led to a slump in energy imports from some OPEC nations, most notably those in Africa, which typically produce lighter grades of oil similar to the North American blends. U.S. crude production jumped 20 percent in a year to 7.37 million barrels a day in the week ended May 3, the highest level since February 1992, data from the U.S. Energy Department’s Energy Information Administration show.

U.S. shale is a light crude and doesn’t affect exporters of medium and heavy grades such as Venezuela.

“Every North American barrel pushes out an OPEC barrel,” even though the U.S. doesn’t yet export much crude, said Roy Mason, founder of tanker tracker Oil Movements, in England. “It’s a problem for OPEC now.”