Dilbit, what is it?

Crude oil is tested at TransCanada's Keystone Hardisty Terminal to ensure it meets strict specifications before entering the Keystone Pipeline for transport to the United States.

Crude oil is tested at TransCanada’s Keystone Hardisty Terminal to ensure it meets strict specifications before entering the Keystone pipeline system for transport to the United States.

 

A lot of questions have been raised recently about the crude oil produced from the Canadian oil sands and how it affects pipelines. Is it really crude oil? What is it mixed with before it goes into the pipeline? Is it more corrosive or dangerous than conventional crude? Does it float or sink if it spills in water? These are some of the most frequent questions we are asked, so we thought it would be helpful to provide some answers and present the facts about this important energy product.

Is it really crude oil?
Yes. The substance recovered from the Athabasca oil sands is sand that is saturated with bitumen. Bitumen is the remains of carbon-based plants and animals that have been transformed into an energy rich “fossil fuel” by millions of years of decay and compression underground. These naturally-occurring deposits in northern Alberta have been utilized for various purposes by humans for centuries. Using steam and hot water, raw bitumen is separated from the sand. Bitumen is then either upgraded by removing carbon and adding hydrogen to create synthetic crude oil or blended to create synbit or dilbit. Synthetic crude oil, is a form of crude oil that closely resembles conventional light crude oil. Dilbit and synbit approximate the characteristics of typical conventional heavy crude oil. Oil sands-derived crude oils have been travelling through North American pipelines for decades and are well understood by the industries responsible for producing, transporting and refining them.

While every batch of crude oil has its own unique characteristics, they all must meet the specifications of the refineries that process crude oil into gasoline and other refined petroleum products. TransCanada’s Keystone Pipeline transports more than 500,000 barrels per day of Canadian crude oil to U.S. refinery markets and has transported more than 340 million barrels since it opened in July 2010. Each batch of oil that enters the pipeline at our Hardisty Terminal is tested for viscosity, temperature, water content, suspended solids and other characteristics. The physical and chemical properties of the crude oils transported by the Keystone are very similar to the heavy crudes refined in the U.S. from sources including California, Venezuela, Nigeria and Russia.

What is dilbit mixed with before it goes into the pipeline?
To reduce the viscosity of bitumen so that it flows efficiently in a pipeline, bitumen is often diluted with a light petroleum liquid to produce diluted bitumen, or dilbit, which is a form of crude oil that is carried in many pipelines. The diluent is typically a liquid that made from condensed natural gas and is a thinning agent used in many industrial processes.

Synthetic crude oil can also be used as a diluent, in which case the product is called synbit.

Is dilbit more corrosive or dangerous than conventional crude?
No. Several studies have shown that there is no difference in safety or risk for pipelines carrying bitumen-derived crude oil compared to traditional, lighter crude oils. An analysis of pipeline failure statistics in Alberta by the Energy Resources Conservation Board did not identify any significant differences in failure frequency between pipelines handling conventional crude versus pipelines carrying synthetic crude oil.

Studies by petroleum chemical experts have also concluded that diluted bitumen behaves the same as other forms of crude oil and does not lead to more corrosion in pipelines. A study released earlier this year by the U.S.-based Batelle Memorial Institute concluded that “diluted bitumen poses no more of a corrosion risk to pipelines than conventional crudes.” Similarly, a study by Alberta Innovates found that diluted bitumen may actually be less corrosive to steel pipelines than conventional crudes. And an international standards organization has also concluded the same based on new research involving scientists from Natural Resources Canada.

Does it need to be heated or pressurized to move in a pipeline?
Oil sands crudes are transported at similar pipeline pressures to other heavy crude oils. All oil pipelines are required to operate under a designated maximum operating pressure (MOP) that is based on the strength of the pipe. Our Keystone Pipeline has a maximum operating pressure of 1308 psi, which is the U.S. industry standard maximum operating pressure at 72 per cent of the specific minimum yield strength for the pipe.

Raw bitumen is sometimes heated in order to transport it relatively short distances through pipelines, but the synthetic crudes and blended bitumen transported in Keystone are not heated for transportation. Some warming occurs due to the friction of oil moving through the pipeline, but the average temperature in the Keystone Pipeline is 37 degrees Celsius (98 Fahrenheit).

Pipeline operating pressure and temperature are among the many factors that are regulated by authorities in Canada and the United States. TransCanada is serious about maintaining the safety and integrity of our infrastructure. Last year, we spent over $800 million on long term maintenance and operating improvements to our pipelines across North America.

Does it float or sink if it spills in water?
Oil sands-derived crudes behave the same way as conventional crude oil, which floats in still or slow-moving water. Crude oil does sink if it is allowed to weather and mix with dirt over time, making a swift response to a spill in water critical. In turbulent water, it is typically driven to the bottom of the river where it tends to stick to rocks, which can make clean-up more difficult.

For further information, the American Petroleum Institute has produced an excellent fact sheet on diluted bitumen available here.