BERTHOLD Enbridge Pipelines North Dakota is looking to tighten its quality standards for crude oil after discovering a high concentration of dangerous hydrogen sulfide gas at its Berthold station.
Since filing its intent with the Federal Energy Regulatory Commission on May 8, Enbridge has been working with Bakken shippers who have demanded more details before the new standards can go into effect.
Enbridge seeks to modify its tariff to establish a right to reject shipments containing more than 5 parts per million of hydrogen sulfide. A sample found at the Berthold station was at an extreme level of 1,200 ppm.
Hydrogen sulfide is a colorless, flammable vapor with a rotten egg smell and potential to cause serious health effects. It is produced by bacterial breakdown of organic materials and occurs naturally in crude petroleum and natural gas.
Enbridge's intent is to keep employees safe and maintain the quality of crude desired by the end market, said Katie Haarsager, Enbridge spokeswoman, Minot. She said some other common carrier pipelines serving the Bakken already limit the allowable hydrogen sulfide in crude oil that they transport.
Bakken shipper Plains Marketing protested Enbridge's proposal, citing difficulty with the immediate implementation and vague language. Plains Marketing agreed that it is appropriate for Enbridge to establish a hydrogen sulfide threshold but added that Enbridge's proposal gives it an "improper degree of discretion to accept or reject thousands of barrels of crude oil for shipment on its system and creates an enormous potential for undue discrimination."
Plains Marketing last week asked FERC for a technical conference, at which Enbridge would outline the specific standards and procedural mechanisms that it wants to use. Murex Petroleum, Hess and Marathon Oil also filed to intervene, indicating their interest in the case as affected parties.
Haarsager said Enbridge is working with its shippers to address their questions and achieve the level of safety that everyone wants to see.
"It's really good to see the industry step forward and recognize that safety is top priority," she said.
Under Enbridge's proposal, crude oil with hydrogen sulfide above 5 ppm could be accepted if there is an ability to blend that sour crude with higher quality sweet crude to create a safer product or otherwise manage the sour crude safely. However, Enbridge indicated that the company needs advance information from shippers to make these decisions.
"We want to work with our shippers to know where it's going into the system, how much it is and where we are going to be delivering so that our employees can be protected to the best of our ability," Haarsager said.
Exposure to hydrogen sulfide is regulated by the Occupational Safety and Health Administration. Low concentrations, up to 10 parts per million, can irritate the respiratory system and can cause burning and tearing of eyes, cough and shortness of breath. At high levels, more than 200 parts per million, exposure can be fatal.
Enbridge has monitoring and vapor suppression systems at its Berthold station that serve as safety mechanisms.