BISMARCK - More than 28,000 gallons of an oily brine that's a byproduct of oil production leaked from a tank in western North Dakota's Billings County and reached a tributary of the Little Missouri River before freezing, the North Dakota Health Department said.
Kris Roberts, an environmental geologist with the North Dakota Health Department, said Midland, Texas-based BTA Oil Producers immediately reported the spill on Sunday at a well site 15 miles northwest of Medora.
Roberts said about 650 barrels of saltwater and 20 barrels of oil spilled from a tank at the well and migrated about a quarter mile before freezing in a dry drainage, about four miles from the Little Missouri River. A barrel is 42 gallons.
Roberts said the spill has been contained and state regulators have been on site since Monday, taking water quality samples.
"We got people on it quickly and we've got a plan to clean it up," Ben Grimes, operations manager for BTA Oil Producers, said Tuesday.
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Grimes said the mixture of saltwater and oil - called produced water - was being held at a well site tank that failed.
"A gasket gave way," he said, citing the cause of the leak.
The spill happened on private land and federal land. The state the U.S. Forest Service both will oversee the cleanup, Roberts said.
The company has hired a contractor to clean up the site, he said.
Roberts said the leak occurred at an older well that was not targeting the rich Bakken or Three Forks formations. Saltwater produced from those formations can be many times more salty than ocean water.
The so-called produced water that leaked from BTA Oil Producers' well appears to have a very low salinity because of the short time it took to freeze, Roberts said.
"It's not as strong of salt content from a Bakken well," Roberts said.
