Crude Oil

Crude oils, including bitumen, typically contain a diversity of naturally occurring hydrocarbon molecules, ranging from lighter (i.e., smaller) components through to heavier or larger molecules. The refining process separates out the various components needed for our everyday use. These include fuels such as gasoline for our cars, fuel for airplanes, diesel fuel (or distillate) for trains and trucks and home heating oil. Petroleum is also used in the manufacture of hundreds of widely-used products such as plastics, solvents and lubricants, as well as raw materials for manufacturing petrochemicals. Crude oils are named according to their characteristics and origins, and classified according to their weight per unit volume (density). Crude oil has historically been referred to as conventional crude, which is generally found deep underground by drilling. This crude typically has a density range of around 800 kg/m3 to 900 kg/m3 (80% to 90% that of water).

Most conventional crudes have varying amounts of the heavier components usually associated with bitumen. The heavier components can be refined into heavy fuel oils or even asphalt, or they can be “split” using a more extensive refining process into lighter petroleum products for other uses.

Bitumen

Bitumen is a heavier, thicker form of petroleum. It’s a product that occurs in numerous deposits around the world. The oilsands of northern Alberta are one of the largest known deposits of bitumen. Sometimes, bitumen is found near the surface mixed in with sand and other geological material, while in other instances, it is found at greater depth below the surface under hundreds of metres of rock.

This oil doesn’t have as much of the lighter hydrocarbon molecules when compared to conventional crude. In order to make it flow through a pipeline, either of two approaches is most commonly used. In the first approach material is partially refined at a facility called an upgrader. This process effectively takes the larger molecules and ‘splits’ them into mid-size molecules suitable for transporting via pipeline. This material produced is called synthetic crude and is very similar to conventional crude.

In the other approach, natural gas liquids or condensate (diluents) are added to reduce the bitumen density and viscosity. Synthetic crude oil may also be added for this purpose. Adding these lighter hydrocarbons to bitumen allows it to flow more easily. While not adding all of the various lighter molecules found in conventional crude oil, enough light material is blended in to make the product flow readily and meet pipeline specifications. The resulting homogeneous mixture is referred to as “Diluted Bitumen” or Dilbit. Multiple sources for diluent are available and all are petroleum liquids. The resulting material, Dilbit, therefore has a makeup of light and heavy hydrocarbon molecules. The resulting density is the average of the materials blended. In the refining process, this material requires more refining to turn it into mid-range materials such as diesels and gasolines.

A third alternative is also available, although not a viable option for long distances. This process uses a heated pipeline that reduces the viscosity of the bitumen and allows it to flow in the pipeline. Heated pipelines are generally used only for short distances and connect production facilities to upgrading facilities.

More information about bitumen can be found here.

Diluted Bitumen

Some people think diluted bitumen sinks in water. The fact is that with a maximum density of 0.94, diluted bitumen is lighter than water (density 1.00) and seawater (density 1.03).

Additional research is taking place to quantify how the diluted bitumen reacts over time in water, with wave action, fast-moving currents, different sediment levels and various other factors.

Other studies have recently been conducted or are underway. Here are a few of them:

Is bitumen more corrosive than other crude oils?

Modern scientific studies completed on this topic have concluded there is no evidence that bitumen is more corrosive than other crude oils. Generally, corrosion is a function of the non-hydrocarbon components such as water, chlorides or sulphur compounds. Transporting Dilbit does not involve risks materially different from crude oils and these risks can be managed through existing programs. Trans Mountain and other major pipelines have been moving Dilbit for about 30 years. 

The Canadian Energy Pipeline Association (CEPA) recently published a study conducted by Penspen Integrity, a division of the UK-based Penspen Limited, confirms that diluted bitumen is not more corrosive than conventional crude. Read the report.

The Transportation Research Board of the National Academies has undertaken a Study of Pipeline Transportation of Diluted Bitumen. Visit Transportation Research Board for a description of what this study will entail.

How would dilbit behave in the event of a marine spill?

In July 2007, a third-party contractor struck the Trans Mountain line and caused a spill in Burnaby, BC. The product that was in the line at the time of the spill was Albian Heavy Synthetic (AHS), which has properties very similar to Dilbit. Some of this product ended up in storm drains and was released via storm sewer pipes onto the ocean floor of Burrard Inlet. The material rose to the ocean surface, where it was cleaned up using conventional methods with a recovery rate of almost 95 percent. The ocean floor sediments surrounding the release site have been tested each year since the spill, and only very low concentrations of residual oil compounds have been detected.

In the case of any spill, response time is critical. A rapid response means that the spilled product has less time to disperse and to weather, ultimately making the cleanup process more efficient and more predictable.

Visit www.itopf.com/marine-spills/ for more information about marine oil spills.

Definitions

SUPER LIGHT PETROLEUM: Means all Petroleum with a Density less than 800 kilograms per m³ or a viscosity up to but not including 2 cSt as measured at Carrier’s Reference Line temperature. Generally a representative Super Light Petroleum includes but is not limited to: Gasoline, Alkylate, and Iso-Octane.

LIGHT PETROLEUM: Means all Petroleum or blended Petroleum with a Density equal to or greater than 800 kilograms per m³ but less than 880 kilograms per m³ or a viscosity up to but not including 30 cSt as measured at Carrier’s Reference Line temperature. Generally a representative Light Petroleum includes but is not limited to: Rainbow, Pembina, and Diesel, or as blended.

MEDIUM PETROLEUM: Means all Petroleum or blended Petroleum with a Density equal to or greater than 880 kilograms per m³ but less than 904 kilograms per m³ or a viscosity up to but not including 100 cSt as measured at Carrier’s Reference Line Temperature. Generally a representative Medium Petroleum includes but is not limited to: SSS, or as blended.

HEAVY PETROLEUM: Means all Petroleum or blended Petroleum with a Density less than 927 kilograms per m³ or a viscosity up to but not including 250 cSt as measured at Carrier’s Reference Line temperature. Generally a representative Heavy Petroleum includes but is not limited to blended OSP.

SUPER HEAVY PETROLEUM: Means all Petroleum or blended Petroleum with a Density of up to 940 kilograms per m³ or a viscosity up to 350 cSt as measured at Carrier’s Reference Line Temperature. Generally a representative Super Heavy Petroleum includes but is not limited to: Cold Lake and AHS, or as blended.

More information can be found about the properties of specific light, synthetic and heavy crudes here: crudemonitor.ca