Bakken similar to other light crudes, study for NDPC finds

Bakken crude oil is similar to other North American light, sweet grades and does not pose a greater rail transportation risk than other transportation fuels, a study commissioned by the North Dakota Petroleum Council (NDPC) concluded.

The study by Turner, Mason & Co., a Dallas consulting engineering firm, also showed that Bakken crude is consistent throughout the basin with only minor geographic variability in gravity, NDPC said as it released the findings on May 20.

“This is the third independent study to confirm that Bakken crude does not significantly differ from other crude oils and poses no greater risks than other flammable liquids authorized for rail transport,” said NPDC Vice-Pres. Kari Cutting.

This most recent study reached similar conclusions to one commissioned by the American Fuel & Petrochemical Manufacturers (OGJ Online, May 15, 2014). They also are consistent with test results from nearly 250 crude oil samples that American Petroleum Institute members have already shared with the US Department of Transportation, API said separately.

“It is essential to separate fact from fiction as we work to enhance the safe transportation of crude oil,” API Pres. Jack N. Gerard said on May 20. “Multiple studies have now debunked the idea that Bakken crude is meaningfully different than other crudes.”

Gerard added, “This data will allow industry and regulators to base actions on science rather than speculation as part of our comprehensive approach to addressing concerns regarding the transportation of crude by rail, which includes prevention, mitigation and response.”

In the Turner, Mason study for NDPC, data show that Bakken crude has:

• An average API gravity of 41°, similar to other light crudes.

• An average vapor pressure of 11.5 to 11.8 psi, which is 61% below the vapor pressure threshold limit for liquids under federal Hazardous Materials Regulations.

• A flashpoint of less than 73° F., which is within normal range.

• An average initial boiling point near 99.6° F., which is within normal range.

• And an average sulfur weight of 0.14, which indicates low corrosivity.

These characteristics all fall well within specifications and design thresholds to safely transport crude using existing DOT 111 railcars, according to NDPC. The findings also confirm that Bakken crude has been and continues to be properly classified under current regulations as a Hazard Class 3 Flammable Liquid, Packing Group I or II.

Fifteen well sites and seven rail loading facilities covering the entire Bakken area were sampled and tested multiple times over one month, ending in late April. NDPC said the broad slate of tests and the more than 150 samples analyzed make this one of the most comprehensive independent studies of its kind ever conducted in the US.

Two smaller studies also were completed, the state petroleum council said. The first compared the quality of the crude as loaded in North Dakota to the quality at discharge, more than 1,500 miles away. The data indicated no significant changes in transit. The second looked at the effects of seasonality, which showed that the vapor pressure stayed within a relatively narrow range, despite widely varying seasonal temperatures.

The study also found that one of the tests DOT requires to determine the packing group for flammable liquids like crude oil is not optimal. The limitations of the test required for measuring initial boiling point can result in the same crude sample being assigned to Packing Group I or II. API is working to determine improved, more precise classification standards for assigning flammable liquid packing groups, NDPC said.

“Since Bakken crude is no more dangerous than other products moved by rail, accident prevention efforts focused track maintenance, staff training, and train speeds will be the key to improving safety,” Cutting said.

Contact Nick Snow at [email protected].