PETRO PERIL: The cross-country odyssey of Bakken crude

petroperil trails

By Bryce Gray

From its Late Devonian and Early Mississippian resting place of some 300 million years, the light, sweet crude of “Bakken gold” is extracted through hydraulic fracturing, or “fracking,” and horizontal drilling techniques. As soon as the oil bubbles to the wellhead at the surface, the process of converting it into a market-ready commodity begins in earnest.

At the wellhead, the crude is stored in stock tanks, and eventually undergoes preliminary heating to remove water.

Natural gas also exits the wells through the drilling process. Satellite imagery shows widespread flaring that sets the region aglow at night, as approximately 30 percent of the area’s natural gas is burned off. When possible, the gas is captured and stored separately from tanks of crude, to be processed into fuels such as propane or butane.

Satellite imagery shows widespread natural gas flaring
Satellite imagery shows widespread natural gas flaring that sets the region aglow at night, as approximately 30 percent of the area’s natural gas is burned off (Source: NASA)

Ryan Couture, an energy consultant at engineering firm Turner, Mason & Company, said that flaring is not intentionally wasteful, but rather an unfortunate casualty of economics.

“The short answer is there’s not the infrastructure in place to collect it,” he said. “Because as the expansion was going on so quickly in the Bakken for drilling, it’s easier to throw a couple tanks there for liquids, but for the gas, you really need to pipe it.”

After separating out the water and gas, the crude enters the shipment phase of its lifespan. At this stage, it is most commonly loaded into cylindrical model DOT-111 rail cars, which are under growing scrutiny in terms of safety and design.

Those calls have led railroads to voluntarily phase in the use of CPC-1232 rail cars. Billed as being a safer alternative to the maligned DOT-111 models, the design of the 1232 incorporates thicker tanks and head shields positioned at either end of the car, to serve as a buffer in the event of a collision. Despite their goal of enhanced safety, these cars, too, have been involved in explosive derailments, including the accident near Galena, Illinois, in March.

Geographic distribution of Bakken crude
↑ Click on chart of interactive version). While the amount of crude oil traversing the nation by rail has climbed steadily, the destination has shifted dramatically. (Data: U.S. Energy Information Administration)

In 2010, rail accounted for shipment of approximately 30 million barrels of crude oil. But the prolific Bakken oil boom helped drive that total to 270 million barrels in 2014. A growing percentage of Bakken oil is destined for refineries on the East Coast, which requires that it first pass through Chicago, the nation’s preeminent rail hub.

Once the crude arrives at the refinery, it is finally processed into usable petroleum products, such as gasoline, jet fuel and diesel fuel. This is most commonly done through a distillation process that heats and separates the fuel into products of different weights, determined partially by the demands of the market (lighter fuels, such as gasoline, are typically of greater value than heavier products, like residential fuel oil.)


The number of high-profile oil train explosions associated with the Bakken oil boom have caused many to question whether the fuel source is more volatile and prone to combustion than other crude oils.

As a light crude, technically Bakken oil is more volatile than heavier hydrocarbons.

“All light crude oils are volatile compared to heavy oils like tar sands,” said Couture. “But it’s consistent with other light crudes.”

Nicole Leonard, an analyst with Bentek Energy, an industry analytics firm, echoed that the properties of Bakken crude are largely consistent with other crudes, but noted that analysis she’s seen places it “on the high end of vapor pressure” compared to similar oil types.

Based on samples tested through May 2014, the federal Pipeline and Hazardous Materials Safety Administration determined that Bakken oil is classified correctly under their safety guidelines, but does exhibit attributes such as a higher gas content, higher vapor pressure and lower flash point.

“We conclude that while this product does not demonstrate the characteristics for a flammable gas, corrosive liquid or toxic material, it is more volatile than most other types of crude – which correlates to increased ignitability and flammability,” the PHMSA report stated.

One assertion circulating in the wake of oil train derailments is that the Bakken crude “separates out” during early-stage processing and shipment, concentrating its more volatile components in one place.

Industry insiders, however, insist that separation – either at the wellhead or naturally during transit – does not occur until the material reaches the refinery.

“When processing to get the water out at the wellhead, there’s not a ton of separation,” said Leonard. “Once you get to the refineries you have to heat it up to a certain temperature to get the different refined products.”

Couture also refuted the notion that Bakken crude undergoes separation prior to the refining process.

“You’re not going to get crude oil stratifying,” he said, noting that tank cars are equipped with specially designed roofs to minimize vapor space.

“You’re gonna need to make it indestructible in order to not have a problem,” he said. “You’re talking tens of tons colliding into each other at 50 mph.”— Ryan Couture

He believes that Bakken’s newly gained notoriety in the wake of recent derailments is a function of increased risk, with so much oil moving on the nation’s rail system.

“You’re increasing your odds that you’re going to have more instances,” Couture said, noting that the rail trip of oil in Texas is only 400 miles compared to the 2,000-mile trek from North Dakota to the East Coast. “So you have five times the distance and 10 times the crude, [meaning] you have 50 times the odds that you’re going to have a problem.”

As for the explosive recent accidents, Couture chalked that up as an occupational hazard of getting a fuel source to distant markets and refineries.

“These cars are not exploding sitting on the tracks,” he said. “They’re catching on fire after they derail while in motion and the rail cars have actually breached.”

With rail lines traversing densely populated towns and cities around the country, ensuring public safety requires that somebody – whether public or private – invests in more stringent safeguards.

“BNSF has advocated for a safer tank car in the movement of crude oil and finally setting a new federal standard will get the next generation tank car into service and substantially reduce the risk of a release in the event of an incident,” said Roxanne Butler, media relations director for BNSF.

But Couture said engineering against the inherent risks of oil shipment is not feasible for rail companies.

“You’re gonna need to make it indestructible in order to not have a problem,” he said. “You’re talking tens of tons colliding into each other at 50 mph.”


The highly publicized rash of oil train derailments has renewed some discussion of whether pipelines – themselves a controversial delivery method– represent a safer alternative for distribution.

“Basically a pipeline is the preferred choice in almost any circumstance,” said Sandy Fielden, a Texas-based analyst at RBN Energy who writes a blog about the Bakken region. “It’s cheaper, it’s more efficient and it’s safer.”

Fielden said that although rail is a less attractive option than pipelines, it won’t go away as a primary shipment option for a number of reasons, including distance. Most notably, pipeline access to refineries along the densely populated East Coast is “unlikely” to happen.

As for shipment to the West Coast, “the Rockies kind of get in the way,” Fielden noted bluntly.

The investment of time and money required to construct pipelines also helped shift the burden to railroads.

“One of the reasons rail was popular is that it takes a lot of time to construct a pipeline,” said Fielden.

Those constraints mean that railroads will continue to bear a disproportionate share of Bakken oil for the foreseeable future, leaving residents near rail lines to hope that new standards for rail cars will keep them out of harm’s way.

Some area residents maintain that those regulations are not enough.

“The new rules out of the D.O.T. are too little too late,” said Lora Chamberlain, an organizer and spokesperson for Chicagoland Oil By Rail, a coalition of concerned citizens. Chamberlain said that the new guidelines are full of loopholes, and can be avoided if certain numbers of oil cars aren’t linked together consecutively.

“It’s just Swiss cheese. There are so many ways for the railroads to get around it. Plus, we don’t think it’s the cars,” she said. “We think it’s the cargo.”

petro peril 250One in an ongoing series of stories examining the impact of millions of gallons of volatile crude oil as it passes in rail tanker cars through densely populated Chicagoland each day.