Learn about dilbit

What is Dilbit ?



The Northern Gateway project, if implemented, will be sending the product Dilbit through a pipeline to be built between Alberta and a terminal at Kitimat, BC, for export to Asia via oil tankers. Similarly, the Trans Mountain pipeline will be transporting Dilbit between Alberta and Burnaby, BC, en route to the Pacific and Asia.

Dilbit is NOT crude oil. Dilbit is a product resulting from the mixture of high viscosity bitumen from the Alberta oil sands with a low viscosity “condensate” to facilitate the flow of the bitumen through the pipeline.

We have argued that the Northern Gateway project is fraught with unacceptable risks, and have raised objections to the marine aspects of the tankers’ navigation through the challenging channel waters between Kitimat and the Pacific Ocean. Similarly, we have raised concerns about the navigational challenges along Burrard Inlet.   In addition, there are also significant environmental risks  associated with Dilbit as a result of its behavior after a possible spill and the toxicity of the condensate.

Let us consider first the condensate itself.

Natural gas condensate is a low-density mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced in many oil and natural gas fields. Raw natural gas may come from any one of three types of oil or gas wells:

  • Associated gas coming from crude oil wells
  • Non-associated gas coming from dry gas wells
  • Wet gas coming from condensate wells

“Condensate” is the result from condensation of raw natural gas, after cooling it to temperatures below the hydrocarbon dew point. The resulting liquid has a low viscosity and many uses, one of them being its blending with high viscosity bitumen from the oil sands to improve its transportability. Condensate is composed of hydrocarbons such as propane, butane, pentane or other hydrocarbons with additional carbon atoms. The condensate may contain additional impurities such as hydrogen sulphide (which is very corrosive),  methyl , ethyl,  as well as aromatics like benzene toluene and ethylbenzene. Some of these components, like benzene, are known carcinogens.

What would happen to condensate when exposed to the atmosphere? The liquid will readily evaporate, and a condensate spill clean-up will largely rely on concentration or isolation of the spill area, absorption  with inert material, dyking ahead of the spillage to prevent drainage to sewers or surface waters, all attempting to avoid environmental contamination.

In a Dilbit spill, the condensate will evaporate leaving the heavy bitumen behind. The behavior of the residual heavy bitumen in marine water is not fully understood and is still the subject of experimental research. Whether it will sink or not (affecting the effectiveness of the clean-up effort) will depend on the salinity and temperature of the water column, as well as the turbulence produced by currents and waves.

The toxic hazards of condensate have been documented in several industrial publications available online. A list of these references includes, but it is not limited to, the information produced by the following industrial sources:

  • Cenovus Energy Inc.  www.cenovus.com
  • Plains Midstream Canada www.plainsmidstream.com
  • P. Morgan Ventures Energy Corp. www.jpmorgan.com
  • P. Energy www.jpmorgan.com

These publications detail the condensate properties, many of the common associated hazards and recommendations related to a condensate-related accident. For example:

  • Condensate is a colourless to straw-coloured liquid, with hydrocarbon odour, which readily vaporizes at atmospheric pressure and it is extremely flammable
  • Vapours are heavier than air
  • Toxic, with possible long term effects to the aquatic environment and wildlife
  • Toxic to humans, with recommendations to avoid exposure, skin contact and not breathing the vapors; cause of eye damage, nausea, dizziness and headaches
  • Avoiding sparking conditions
  • Remaining upwind during a fire
  • Detailed recommendations to fight fires in the case of ignition, using water only to cool adjacent area, and utilizing specific firefighting techniques: foam, CO2, or dry chemicals
  • First responders must use chemical resistant clothing, positive pressure breathing apparatus, and eye protection
  • Short term health hazards related to exposure to vapors include: eye and skin irritation, inhaling difficulties, affections to the central and peripheral nervous system.
  • Chronic or long-term effects may include: cancer risk, effects on the nervous or cardiovascular system, and seizures or fatal risks due to repeated exposures.

Certainly, the consequences of exposure to condensate after a spill or an explosive accident are not a trivial matter. How frequent have these accidents been?

Transportation accidents involving a mixture of condensate and bitumen are still very few, but are due to become more frequent following a proposed large increase in Dilbit shipping through the railways, tankers and pipelines. Certainly, explosions of gas pipelines with severe consequences have occurred in the recent past. For example, a gas pipeline exploded in the residential neighborhood of San Bruno, south of San Francisco, California, on September 9, 2010. This accident destroyed 38 homes, killing 8 people and injuring many more. The National Transportation Safety Board (NTSB) charged the utility transporting the gas with providing misleading information regarding pipeline testing and maintenance procedures, and generally following procedures that did not meet Federal safety standards. Another explosion occurred July 31, 2014, in the residential neighborhood of Kaohsiung, Taiwan, killing 31 people, injuring over 300 and causing extensive damage to buildings and homes. The blasts ripped up 6km of roads, and black-outs were triggered throughout the electrical grid. Although these historical events involved just gas, condensate explosions could equally follow pipeline cracking or ruptures, with the possible additional complication of a subsequent bitumen spill.

More information on condesate and Dilbit is provided online as follows:

  • Wikipedia, search for Natural Gas Concentrate (modified July 2, 2014)
  • Safety Data Sheets (SDS’s) published by the industry as required by regulation: for example,


Cenovos Energy Inc.

Plains Midstream Canada

J.P. Morgan Ventures Energy Corp.

  • Material Safety Data Sheets (MSDS’s) published by industry as required by regulation: for example:

Encana Services Company Ltd.



  • Latest Report on Dilbit from Environment Canada, Fisheries and Oceans and Natural Resources Canada [add]


Environment Canada, Fisheries and Oceans, and Natural Resources Canada: Latest Report on Dilbit Behavior, November 2013

View PDF Environment Canada Dilbit Nov 2013

Just before the Joint Review Panel released their report in December 2013, the Canadian Government released a report on a small study that tested the behavior of two types of diluted bitumen under simulated weathering.   This project was undertaken as part of the Government of Canada’s strategy to develop a “World Class” prevention, preparedness and response regime for oil spills from ships.

“The behaviour of the diluted bitumen products was studied under laboratory conditions in three phases. First, the properties and composition of two samples representative of products currently being shipped in Canada were measured before (fresh) and after (weathered) exposure to environmental conditions. Secondly, the potential for evaporation, exposure to light, mixing with saltwater, and sediments in the saltwater to affect whether diluted bitumen products float or sink in saltwater was examined. Finally, the effectiveness of two existing spill treating agents meant to disperse spilled oil products was evaluated. ” (p5)

Can weathering cause sinking?

In general the report finds that weathering (evaporation and exposure to light) is not sufficient to cause the two types of diluted bitumen to sink in “fully salt marine waters”.  This conclusion is drawn from the data shown in the figure below, where AWB and CLB are the two types of diluted bitumen and the data series fresh, W1, W2, W3 and W4 represent different amounts of weathering (p46):


Douglas Channel contains a large amount of fresh water

What is not mentioned in the report, however, is the fact that the water in Douglas Channel cannot be assumed to be “fully salt” as there are often layers of less dense fresh water floating on top of the more dense salt water.  If weathered bitumen is heavy enough to sink through fresh water, and a layer of fresh water sits on top of the salt water in Douglas Channel, the weathered bitumen could sink below the surface and remain trapped at the boundary between the fresh and salt water layers.

This is a topic that was discussed in the April 25, 2013 hearing as well.  Although the discussion was brief, it referenced a report conducted by ASL Enviromental Sciences (Sidney, British Columbia) in 2010: Marine Physical Environment, Enbridge Northern Gateway Project.

View PDF ASL Report

“The temperature and salinity profiles in the CCAA consistently reveal distinct upper layers ranging from a few metres to 10 to 15 m depth, characterized by much-reduced salinities compared to the underlying deeper waters. From late spring through the fall months, the salinities are much lower than those at depth, resulting in a large density gradient between the upper layers and the remainder of the water columns. These lower salinities result from the large amounts of freshwater land runoff and direct precipitation. The upper layers also have higher water temperatures in spring, summer and fall.” (p 24)

 If Douglas Channel contains a thick layer of fresh water, and diluted bitumen sinks in fresh water, how can a spill be tracked and cleaned up?

What were the JRP’s findings?

View JRP Report Vol. 2

Disagreements between Environment Canada and Transport Canada

In general, the Joint Review Panel’s summary of this issue seems to track the items that were debated during the review, but fails to offer a critical analysis of the information presented.  Despite an obvious disagreement between Transport Canada and Environment Canada as to whether or not diluted bitumen can be recovered in the event of a marine spill, the Joint Review Panel chooses to draw the conclusion that Northern Gateway’s plans are “sufficient”.

Environment Canada said that, in its current form, the response scenarios included in Northern Gateway’s fate and trajectory modelling were of limited value for spill response planning and risk assessment because of uncertainties related to the behavior of the product in the marine environment.  (JRP Report vol 2, p163)

Two pages after this acknowledgement of Environment Canada’s position the report goes on to say:

The Panel finds that Northern Gateway’s extensive evidence regarding oil spill modelling, prevention, planning, and response was adequately tested during the proceeding, and was credible and sufficient for this stage in the regulatory process. (JRP Report vol 2, p165)

They draw this conclusion despite a number of troubling statements, documented earlier in the report, that this product will likely be difficult to track and clean up:

Northern Gateway said that oil may become entrained in the water column by wave- or current-induced water turbulence in freshwater and marine environments. It said that the depth and duration of submergence depends on factors such as oil density and viscosity, wave energy, and size of the oil particles. It said that entrainment in the water column would typically be temporary, and that the oil would resurface in calm conditions. (JRP Report vol 2, p91)

Northern Gateway said that, while dilbit is not likely to sink due to initial weathering alone, if not recovered in a cleanup operation, dilbit weathered over a period of weeks could eventually sink. (JRP Report vol 2, p91)

While dilbit may not sink, it is likely to submerge, making cleanup and tracking difficult.  (JRP Report vol2, p100)

We are left to ask if the Panel is basing its approval on an optimistic view of the conditions under which a spill might occur.  Given the complicated currents and geometry of the Douglas Channel area, is it reasonable to assume that the spilled diluted bitumen can be recovered before it weathers and sinks?  What of the issues mentioned above with tracking overwashed oil, where a significant amount of time and effort may be required to actually locate overwashed oil so that it can be cleaned up before sinking?

More research is needed

Both Environment Canada, Northern Gateway, and the Joint Review Panel agree that more research is required to understand the behaviour of diluted bitumen spilled into a marine environment and the extent to which it can be cleaned up.

Environment Canada referred to its research indicating that the potential for oil to sink depends on many factors, such as evaporation, photo-oxidation, emulsion formation, water temperature, salinity, and oil particle size. It said that uptake of particulate matter is the most important contributor to increased density of spilled oil. It said that experience with previous spills shows that some of the oil could sink, some would float, and some would become neutrally buoyant and temporarily submerged or overwashed. It said that it did not have enough information to make quantitative predictions of dilbit behaviour, and was planning research on the topic. (JRP Report vol 2, p91)

[Environment Canada] also said that additional research would be required regarding the behavior, fate, and environmental effects of the products to be shipped, as the actual behavior of spilled oil depends on the environmental conditions at the time and the physical and chemical characteristics of the product. (JRP Report vol 2, p95)

The Panel finds that research on the behaviour and cleanup of heavy oils is required to inform detailed spill response planning and heavy oil spill response in marine and freshwater environments. Northern Gateway has committed to be responsible for this research. (JRP Report vol 2, p101)

But will the findings of this research be used?

If further research is needed to understand the details of how diluted bitumen behaves when spilled into the environment, is it not premature for the Panel to have approved the project before this research is completed?

Despite requirements to carry out further research on this issue, we are troubled by the Panel’s closing statement on the topic of diluted bitumen cleanup:

In the Panel’s view, the weight of evidence indicates that disagreement among experts on the fate and behaviour of spilled oil is related to specific details that may not be significant from a spill response perspective. Additional research is  required to answer outstanding questions related to the detailed behaviour and fate of dilbit. All parties with technical expertise on the topic were in agreement with this.

The Panel finds that research on the behaviour and cleanup of heavy oils is required to inform detailed spill response planning and heavy oil spill response in marine and freshwater environments. Northern Gateway has committed to be responsible for this research. (JRP Report vol 2, p101)

The first paragraph seems to state that the disagreements among experts are not relevant to the problem of whether or not diluted bitumen can be recovered, while the second paragraph states that more research is required, presumably to resolve these disagreements.

If further research is necessary, the risks of the project should be considered unknown until  this research is completed.  As is the case with other parts of the report, we do not understand the methodology used by the Panel to determine that the risks are outweighed by the benefits, especially if the risks require further research.  The Panel’s approval of the project in advance of the research being completed carries disturbing implications:

  1. Either the Joint Review Panel is comfortable approving the project with an incomplete understanding of whether a spill can be cleaned up, in which case the impacts and their associated costs are also unknown, or
  2. The outcome of this research will not have an impact on the approval of this project

We do not understand how the Joint Review Panel can state that they find the risks to be acceptable yet simultaneously require more research to be completed.  This is misleading and presents a false sense of assurance to the public.

Are you comfortable with this project proceeding if the costs and effectiveness of spill cleanup are unknown?

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