Published November 16 2013
Equipment failure, human error most likely spill causesBismarck - Like lost cell phone calls, most saltwater spills can be traced back to three causes: human error, equipment failure or network problems.
A review of incident reports filed with the North Dakota Department of Health since Jan. 1, 2012, found that connection leaks between valves and piping were the most common cause of spills, accounting for nearly 22 percent of 1,085 spills reported through Oct. 29 of this year.
Lynn Helms, director of the state Department of Mineral Resources, said the valve where the pipe goes into a saltwater disposal facility or tank battery is highly susceptible to corrosion and leaks. But they are typically located on well pads with ring dikes, so leaks should be contained, he said.
Tank overflows were the second most common cause of spills, at nearly 19 percent. Human error is most often to blame in such cases, as operators continue to pump saltwater into a tank that’s already full, Helms said. Automated controls that are supposed to shut off the pump when the tank is full also have been known to fail, he said, adding that’s why the state requires a clay liner underneath the tanks and dikes around the well site.
Fire was blamed as the cause in only 20 incident reports, but it’s an issue that’s been getting more attention lately. A saltwater tank exploded Nov. 7 at a disposal well site near Alexander, spilling about 2,700 barrels of saltwater and oil and causing 13 tanks to catch fire. The cause of the explosion hasn’t been determined, but Helms said many such fires are caused by lightning or discharged static electricity.
Oil companies normally use fiberglass tanks to store saltwater because they resist corrosion, but they’re also highly susceptible to static discharges and lightning strikes, Helms said. Oilfield brine also contains small amounts of oil and natural gas that settle at the top of the tanks and are often ignited when lightning or static discharges happen, he said.
Helms said the North Dakota Petroleum Council has been asked to look at the design and construction of saltwater tanks to find ways to prevent fires.