BISMARCK, N.D. — North Dakota regulators say oil companies in September exceeded rules aimed at limiting the amount of natural gas burned off as a byproduct of oil production.

The Bismarck Tribune reports oil companies are supposed to capture 85 percent of natural gas or limit flaring to no more than 15 percent.

State Mineral Resources Director Lynn Helms says companies flared 17 percent of production in September.

He says the flaring of 323 million cubic feet per day was caused by unanticipated maintenance problems with pipelines, natural gas processing plants and compressor stations.

Helms says the increased flaring likely won’t lead to regulators requiring companies to restrict oil and natural gas production.

Information from: Bismarck Tribune,