After measuring elevated levels of hydrogen sulfide in crude oil at its Berthold Station rail loading terminal in Ward County, N.D., Enbridge Pipelines North Dakota has requested permission from the Federal Energy Regulatory Commission to lower the acceptable level of hydrogen sulfide in crude at the Berthold facility to 5 parts per million from the current acceptable level of 10 ppm.
Enbridge said the recent elevated hydrogen sulfide concentration not only poses a threat to the health and safety of Enbridge employees working at the facility, but also to the health and safety of people working in downstream operations where such crude oil is shipped. Enbridge also said shipping such crude out of the Berthold facility runs the risk of having these shipments rejected farther downstream.
On May 5, Enbridge measured hydrogen sulfide vapors in one tank at the Berthold facility at a concentration of 1,200 ppm. Putting that concentration in perspective, the Occupational Health and Safety Administration’s “ceiling” concentration for human exposure to hydrogen sulfide in air is 20 ppm, which is the maximum concentration to which a worker can be exposed during any part of a work day.
Following 1,200 ppm measurement at Berthold, Enbridge submitted a request to FERC asking that the acceptable level of hydrogen sulfide in the corresponding tariff be lowered to 5 ppm. Enbridge also asked FERC to waive the standard 30-day review period and approve the tariff change on May 9.
Plains and Hess protest
Following submittal of Enbridge’s May 8 request, Plains Marketing quickly protested and on May 10 submitted a motion with FERC to intervene in the matter and asked FERC to reject Enbridge’s revised tariff.
Plains says in its May 10 filing that it has historical shipper space of 7,500 barrels of oil per day for the last two years, and its affiliate, Plains Marketing North Dakota, and historical space of 17,500 bopd over the last two years. It says that “…the abruptness with which Enbridge North Dakota has sought to implement the new hydrogen sulfide standard has left Plains in the extremely difficult position of potentially having to shut in up to approximately 4,000 barrels per day of crude petroleum that might exceed the proposed standard.”
Additionally, Plains argues in its May 10 filing that Enbridge only provided a one-day notice of implementation of the new hydrogen sulfide standard, and also argued that two other Bakken-area pipelines, Bridger Pipeline and Belle Fourche Pipeline, recently implemented hydrogen sulfide standards of 10 ppm. Plains also argues that any filing by Enbridge should provide shippers with a 30-day notice to allow sufficient time for the shipping community to comply.
In its filing Plains says it is sympathetic to the health, safety and welfare of Enbridge employees, but notes that other Bakken play pipelines have found hydrogen sulfide standard of 10 ppm to be sufficient protection, and believes that such a standard would be sufficient to address the health and safety concerns raised by Enbridge.
“As to the 5 ppm hydrogen sulfide limit itself, Enbridge North Dakota has not submitted any justification whatsoever to demonstrate that that standard is just and reasonable,” the Plains filing says. “A perusal of its Filing suggests that the Pipeline simply pulled this number out of thin air. While it appears that a 5 ppm standard would have prevented the ‘extremely high level of H2S vapor’ that Enbridge North Dakota found in a recent test, the Filing does not even attempt to justify why a 5 ppm standard is necessary or appropriate to address health and safety concerns. Nor does it so much as state that a 10 ppm standard, or some other less Draconian standard, would fail to achieve these goals.”
On May 15, Hess Corp. also filed a motion to intervene with FERC. In its filing, Hess says that it is a shipper on the Enbridge system in North Dakota and has a direct interest in the matter. “Hess has a substantial interest in, and will be directly affected by, the outcome of this proceeding,” Hess said in its filing. “No other party can adequately represent Hess’ interests. Given Hess’ unique interests in this proceeding, granting its motion to intervene is in the public interest.”
Enbridge responds
On May 14, Enbridge, in turn, filed a response to the Plains protest with FERC. In that response, Enbridge says that if the levels of hydrogen sulfide in crude oil at the Berthold facility remain elevated, the rail facility, which has a daily throughput capacity of 80,000 barrels, would be forced to stop operations until the company could ensure that crude oil being exported through the facility is safe.
Other pipelines, however, have lowered the acceptable level of hydrogen sulfide to 5 ppm, including Tesoro which Enbridge says is downstream of the Enbridge North Dakota system. Enbridge says it needs to ensure that its shipments are consistent with Tesoro’s restrictions. Enbridge adds that its mainline system, which is downstream of the Enbridge North Dakota system, has tariff provisions where crude shipments can be rejected “due to physical or chemical characteristics that may render such crude not readily transportable by the carrier or that may materially affect the quality of other commodities transported by the carrier or that may otherwise cause disadvantage to the carrier.” According to Enbridge, Minnesota Pipeline has a similar provision.
In addition, Enbridge says that it determined that elevated levels of hydrogen sulfide could also have negative effects on the quality of crude oil in its comingled system. “There was a substantial risk that downstream facilities, including rail facilities, would not accept delivery of crude with high levels of hydrogen sulfide resulting in significant economic loss to shippers on the system.”
Enbridge says that any crude oil with a hydrogen sulfide concentration of 5 ppm or less could be accepted, but it doesn’t necessarily preclude accepting crude with a concentration above 5 ppm hydrogen sulfide, and Enbridge wants to obtain information necessary to determine if it should reject certain shipments, and says shippers can still ship crude oil with some levels of hydrogen sulfide as long as Enbridge has advance notice with the information necessary to both protect its employees and to ensure that the crude will be accepted for downstream delivery.
In addition, Enbridge says it can manage the crude quality and human exposure for certain routes and can potentially dilute the hydrogen sulfide concentration depending on the volumes of other crude that will be transported. To that end, Enbridge says it is prepared to accept reasonable amounts of crude with hydrogen sulfide concentrations in excess of the 5ppm standard “so long as the information available with respect to those shipments is sufficient to safeguard system quality and employee safety.”
However, under the proposed tariff, if Enbridge determines a crude shipment with a hydrogen sulfide concentration exceeding 5 ppm is not safe to transport, it can reject it. “Any crude with more than 5 ppm of hydrogen sulfide vapor content would be subject to rejection if Enbridge North Dakota did not conclude it could be transported safely.”
What’s next?
FERC did not agree to the next day implementation of the lower hydrogen sulfide standard as Enbridge requested, but instead has allowed 30 days to act on the matter. That 30-day period begins with a 15-day public comment period, after which Enbridge has five days to respond to the comments. Then FERC has 10 days to issue its decision. The 15-day public comment period began on May 8 when Enbridge filed its initial letter, and extends through May 23. Enbridge then has until May 28 to respond, and FERC will then issue its decision by June 7.
What’s the source of the sulfide?
Bakken crude is generally known to be a light, sweet crude, i.e., it is noted for its low sulfur content, which is certainly one of its attributes. So where is the hydrogen sulfide coming from?
Lynn Helms, director of the Oil and Gas Division of the North Dakota Industrial Commission’s Department of Mineral Resources, believes it’s coming from tradition production sources in the Williston Basin, such as the Spearfish, Madison and Red River formations. Of the 782,812 bopd that North Dakota produced in March, approximately 65,000 bopd came from such non-Bakken or traditional production sources. However, Helms noted in a conference call in March that sulfur had been showing up in some new Bakken wells, so the source of the sulfide at the Berthold facility could be from both Bakken and non-Bakken production.
