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The science of diluted bitumen (Ask NRCan)

On this episode of AskNRCan, scientist Heather Dettman sits down with us to discuss her work with diluted bitumen to improve the transportation of crude oil and better understand how oil spills behave in water.


Joel: Welcome, everyone, to Ask NRCan. This is our podcast series where we sit down with one of our experts to talk about an aspect of the work that we do here at Natural Resources Canada. Today, we’ll be speaking with Heather Dettman, a scientist whose work involves diluted bitumen.

Before we start, I just want to mention that we call the series Ask NRCan because we want to hear from you. The purpose of this show is to share with you, the audience, not only the type of science that we do but also why we do it. So, at the end of the episode, if you have any questions on this topic, please go to Twitter and tweet us using the #AskNRCan. Heather will do her best to answer all relevant questions. Sounds good. Okay, let’s get into it.

[theme music]

Heather, thanks for joining us today.

Heather: Thank you very much for having me.

Joel: Can you start by explaining to us what is diluted bitumen or dilbit?

Heather: Okay, for sure. I guess it would be helpful for people to get an idea about what crude oils are in general, and a useful way to think of crude oil of any type is that it contains a mixture of gasoline, diesel, Bunker B and asphalt. Most people would be very familiar with what gasoline and diesel are — and the Bunker B is just a fuel oil that’s a bit heavier than what diesel is. Then the asphalt is what’s on the roads. All crude oils are made up of that mixture.

Conventional crude has a fair bit of gasoline and diesel components and a smaller amount of the asphalt in it. Diluted bitumen has more of the heaviest component of the asphalt and less of the diesel and the gasoline. And, really, they have all those components, and just to compare the bitumen, it had been a full-range crude at one point in its history. But with geological changes in Alberta, it became close enough to the surface and became biodegraded. Some of the gasoline and diesel components ended up being eaten by the microbes in the ground. Now, the bitumen itself is missing its gasoline. To make the diluted bitumen, the light oils that include gasoline and other parts of the petroleum are added to the bitumen to make the diluted bitumen. Specifically, the dilbit is one of the products made by adding a light oil called CRW condensate. That makes up for those light ends that were missing. There’s also other products they can have synthetic crude oil mixed with it, that would be a synbit. If you have a mixture of the condensate and the synthetic crude oil then that’s a dilsynbit. Dilbit is just one of the products.

Joel: Why is there a need to actually mix the crude oil with a lighter product?

Heather: To transport it by pipeline, the oil needs to meet certain density and viscosity specifications. So, the lighter oils, whatever they are, are added so that the final diluted bitumen product meets the pipeline’s specifications. On one hand, it’s an advantage or it’s necessary for the pipeline. On the other hand, that also makes it a full-range crude, so that it actually is received by the refinery that has ordered for the product. That’s actually an aspect of this — it’s not just sent somewhere to be stored — it’s actually being purchased by refineries at the other end of the pipeline. They need certain mixtures of different kinds of crude oils to be used in the refinery so that they can then make the amounts of gasoline and the diesel and the asphalt that they need for the products on the other end of the refinery. So, by having light oil added to the bitumen, it’s now become a full-range crude and can be handled the same as all the other crudes by the refinery and can be used in that kind of blending, processing, re-engineering that they do in the refinery. To make the slate of transportation fuels and products like asphalt that the particular refinery is using.

Joel: I see. Speaking of transportation, is transporting dilbit any different than transporting any other types of crude oil or gases?

Heather: Well, for oils going into a regular pipeline, diluted bitumen has no higher dangers or concerns than for other types of petroleum products when they are in pipelines. There had been concern in the past about whether it might be more corrosive, but research has shown that it’s not in comparing different types of products. Gases are kind of a different story, but in terms of the liquids, comparing different kinds of crudes, they all have similar kinds of risk factors.

Joel: I see. That makes sense. Obviously, gases must flow much easier down pipelines. So, at NRCan what type of research are we doing involving diluted bitumen?

Heather: At Natural Resources Canada, our original expertise has to do with understanding petroleum and heavy oil, specifically with oil sands production. The kinds of issues they can happen during production, as well as the way it’s being handled in the refinery, trying to improve processes so that they will be lower energy processes or reduce environmental impacts of things like tailings ponds and water quality. All these various kinds of topics around the petroleum industry for producing all crude oils. But we focus mostly on the oil sands area. So, with all of that, we have that background knowledge of oil. Since 2013, we’ve built facilities to monitor, study and develop knowledge toward oil spill behaviour. To do that, we have both lab facilities as well as spill-testing facilities.

Joel: That’s interesting. I think I saw one of the videos on the NRCan YouTube channel. Exactly what do you do in that wave tank — the type of research and tests that you do? That seems like very interesting work.

Heather: It’s actually very difficult to be simulating oil spill tests, especially just in the lab because the standard technique that they use, which is what they call rotary jars, where it’s a jar you put your water in, and you add your oil and you spin it. The key problem with that particular technique is that there’s no evaporation because it’s a closed system, the light ends of the oils stay in it. When you’re out in a spill situation, very quickly those light ends would evaporate, and so the oil is changing constantly as it’s in the water in whatever environment it’s in. So, to have a closed-jar system you can only have a few variables at play. If you’re in a real spill situation, (I sort of joke with my group that we have 15 variables going simultaneously) we are trying to do studies in a systematic way so we can actually identify the mechanisms that are involved as the oil is changing in the water with whatever sediment, with whatever energy, with whatever type of oil. As we do this, we actually are benchmarking and comparing our tests between conventional crude and different types of diluted bitumen. And then as well, because we have all that background petroleum capability, we’re like a little mini-refinery ourselves, where we have the different types of processes where we can change the oil like what goes on in a refinery. So, we can actually do specific processing to the bitumen before making a diluted bitumen out of it to see how that affects the behaviour. With that, we’re really filling in sort of a good map of what kind of molecules in the oil causes which kind of behaviour, under which kind of conditions. With our conditions, we can actually do temperatures. We actually commissioned our tank to have ice on it this past winter, so that going forward, we’ll be able to do winter-spring thaw kind of situations, fall freezing situations, or really try to get at those different kinds of temperature conditions that we certainly have in Canada.

Joel: I see, do you also do any form of more real-life testing as well or it’s more of in a controlled environment?

Heather: We actually are supporting research that is going on out in the field. There are tests being conducted in experimental lakes in Ontario where we are supporting the research that’s going on. We ourselves don’t have a lake or oceanfront that we are working with, but we’re certainly collaborating with others as they are able to do that.

Joel: So Heather, what type of research are you planning to do in the future?

Heather: Well with the Oceans Protection Plan funding that we received we’re actually stretching beyond our own capabilities. What we’re finding here, as I mentioned, is that there are 15 variable kinds of situations when you have a spill. What you can have going on simultaneously is not only the oil changing because of evaporation and viscosity changes as it evaporates, but there’s also a bacteria that can be present. The microbes in the water can actually eat the oil, and so the oil is actually changing as it is in the water. That can influence what parts of the oil can actually be dissolved into the water and that could ultimately affect toxicity.

From understanding all this, we are using our Oceans Protection Plan funding to develop collaborations with toxicologists who will, as we do our tests, monitor the chemistry and see what the oil is doing and how it disperses in the water. Water phase, sediment phase and how much evaporates. So, we are getting that chemical information. But at the same time, we’re taking samples from the water and actually shipping it to toxicologists who are then testing how that water affects fish or other organisms that live in sediment or whatever kind of biota that might be impacted by an oil spill. As well, collaborating with someone who will help us track the changes in microbial populations with having the oil there.

With our tests, we are trying to get as much information as possible simultaneously so we can really tell what affects what when, after an oil spill. People know that the most toxic part for an oil spill is just immediately afterwards because that is when the lighter ends are there. Which is that gasoline fraction, the part that will have the BTEX (benzene, toluene, ethylbenzene and xylene) that’s very toxic to begin with. But we have much less understanding of the effects of the polycyclic aromatic hydrocarbons (PAHs). Because we’re in a tank, we’ve done tests up to four weeks, so we can actually monitor that shift in effects from BTEX to effects from PAHs and how they will change with time. Over the next four years, we hope to provide a fair bit of new knowledge in that inter-relationship of oil weathering, oil biodegradation and the toxicity of the water simultaneously.

Joel: This is really interesting research for sure. Thank you Heather for educating us on diluted bitumen.

Heather: Thank you very much for this opportunity.

Joel: This is the end of the episode, but it doesn’t mean that it’s the end of the conversation. If you have any followup questions for Heather, get on Twitter and tweet at us using the hashtag #AskNRCan. Also, if you are interested in learning more about the scientific work that we do here at Natural Resources Canada, check out our online magazine called Simply Science. We have a ton of great content for you, including articles, videos and previous episodes of this podcast.

If you check out the podcast page for this specific episode, we’ll have links available to any relevant material so you can learn more about diluted bitumen. The best way to find Simply Science is to either Google it or click on the banner from our website at And, as always, if you liked this episode and you are listening to us on Apple Podcast, Stitcher or Soundcloud, please consider subscribing so you can check out any previous or future episodes. I think that’s it for today. Thank you for listening, and we’ll see you next time.

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