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Exxon's Arkansas Tar Sands Spill: The Tar Sands Name Game

Anthony Swift

Posted April 2, 2013

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As the American public becomes acquainted with images of tar sands flowing across lawns, driveways and streets of an Arkansas suburb near Little Rock (for video of the spill go here), Exxon is now making the claim that the crude spilled from its ruptured Pegasus pipeline isn’t technically tar sands. This attempt is reminiscent of the knots that Enbridge tied itself into to deny that the million gallons of tar sands it spilled into the Kalamazoo River weren’t actually tar sands. During that spill Kari Lydersen, a former Washington Post reporter covering the spill for OnEarth Magazine, helped break Enbridge CEO’s about-face,  when after denying that his company had spilled ‘tar sands” for two weeks, told the press:

“No, I haven't said it's not tar sand oil. What I indicated is that it was not what we have traditionally referred to as tar sands oil. ... If it is part of the same geological formation, then I bow to that expert opinion. I'm not saying, ‘No, it's not oil sands crude.' It's just not traditionally defined as that and viewed as that.” Enbridge CEO Patrick Daniel, August 12th, 2010

My colleague Josh Mogerman wrote in detail about Enbridge’s denial – and why the company tried to distance itself from the tar sands crude and the sigificant climate pollution associated with it. It seems that Exxon is borrowing Enbridge’s playbook in this case. Exxon has identified the crude spilled in Mayflower, Arkansas as Wabasca Heavy diluted bitumen. Now the company is making the case that the crude it spilled is not technically ‘tar sands.’ However, Exxon's argument doesn't stand close scrutiny. Let’s look at the key facts.

1. Wabasca Heavy diluted bitumen is produced in Alberta’s Athabasca tar sands region. I’ve included a map showing the Wabasca formation as oil sands rather than heavy oil. The map is from the Canadian Centre of Information – I would link to it but I took it from The Oil Sands Developers Group this morning and the Oil Sands Map section seems to have crashed since then. 


2. Wabasca Heavy Diluted Bitumen is considered by the Alberta Government as tar sands.  In the Alberta Oil Sands Industry’s (AOSID) Spring 2012 Quarterly Update, the Alberta government makes the following characterizations of its tar sands resources:

“There are three major bitumen (or oil sands) deposits in Alberta. The largest is the Athabasca deposit, located in the province’s northeast in the Regional Municipality of Wood Buffalo. The main population centre of the Athabasca deposit is the City of Fort McMurray. The second-largest oil sands deposit is referred to as Cold Lake, just south of Athabasca, with the main population centre the City of Cold Lake. The smallest oil sands deposit is known as Peace River, which is located in northwest central Alberta. A fourth deposit called Wabasca links to the Athabasca and is generally lumped in with that area.” (pg. 2)

 And in its glossary, it defines “oil sands” as:

Bitumen-soaked sand, located in four geographic regions of Alberta: Athabasca, Wabasca, Cold Lake and Peace River. The Athabasca deposit is the largest encompassing more than 42,340 square kilometres. Total deposits of bitumen in Alberta are estimated at 1.7 trillion to 2.5 trillion barrels. (pg. 15)

3. Industry considers Wabasca Heavy diluted bitumen as tar sands. The Canadian oil industry’s crude quality clearinghouse doesn’t list Wabasca Heavy as a heavy conventional crude but as a diluted bitumen – the category for tar sands. In a recent report, the Canadian Energy Pipeline Association (CEPA) referred to Wabasca as “oil sands.”

So given that:

  1. Wabasca Heavy is a diluted bitumen with the physical properties of tar sands;
  2. Wabasca Heavy is produced in the Athabasca tar sands region of Alberta
  3. Wabasca Heavy is considered by both the Alberta government and industry as tar sands.

How does Exxon argue Wabasca heavy is not in fact tar sands? Their argument seems to be based entirely on how Wabasca heavy is produced. Tar sands near the surface is essentially strip mined. When it isn’t nearly the surface, most companies heat water and flood the underground tar sands formations with steam in order to reduce the viscosity of (i.e. melt) the bitumen so it can be recovered from wells in a process called Steam Assisted Gravity Drainage (SAGD).

Exxon makes the point that Wabasca Heavy bitumen isn’t produced by either mining or SAGD, but a process called Solvent Assisted Production (SAP). In solvent assisted production you see, rather than flooding the underground formation with steam to reduce the viscosity of the tar sands bitumen, you flood the formation with a combination of water and polymer solvents to reduce the bitumen’s viscosity. And if you use water and polymer solvents instead of steam, rather than producing tar sands bitumen you get tar sands bitumen.

This transformative process appears to be based on the logic that flooding a reservoir with steam is unconventional while flooding it with water and polymer solvents is conventional. It’s also likely that the logic of Exxon’s argument is predicated on folks not following it quite this far. Cenovus itself, the company using SAP to produce tar sands, describes it as a process used hand-in-hand with typical SAGD methods to produce tar sands. 

Coal is coal whether you use pick ax or shovel. Diluted bitumen tar sands is diluted bitumen tar sands whether you produce it using polymer solvents or steam. And that what was flowing down driveway in Mayflower, Arkansas this weekend.

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Herb FitzellApr 2 2013 07:32 PM

Hello Anthony Swify,
I am working with 350. I only learned about the link between SEIS and Rail this weekend. You know a lot. I was in a protest against Sen. Warner's vote last week and I have to follow up with him, and others. I am working on the underestimation of rail transport costs. I work as a freight rate analyst. I need your help to catch up on the underestimation of rail costs. Any help is appreciated.
Any insights?
SEIS seems to show a transport rate of only 10.00 and 10.75 per barrel. This is low, but I did not estimate $30.
What factors led you to your estimate.
1. Why did they choose dilbit. This seems tricky.
2. What data did they use to reach their estimates?
3. Did the at the RR's provide false low ball rates SEIS used?
Any and all info will be appreciated.
I think you will have my email. Please help. I can send my phone number.
Great work. Congratulations.

EDApr 3 2013 11:23 AM


Michael BerndtsonApr 3 2013 03:25 PM


Here's an interesting primer on tar sands or should we all say CHOPS (Cold Heavy Oil Production with Sand)

My take is that anything from the region of Alberta in question is "oil sands" regardless of flowability. Or pipeline-ability in industry parlance. They may have avoided nomenclature engineering. The Wabaska Heavy Oil whether mined as a consolidated material or in situ modification for sump based extraction by definition it is an "oil sands." Maybe they should have stayed with "Tar Sands." That has been the historical term up until the mid aughts when Alberta made its PR push for development. I guess oil sounds better than tar. Goo-ability may become the next physical property measurement.

Reg CurrenApr 3 2013 05:57 PM


Any spill is unfortunate. Though, we need to clarify with you that Cenovus Energy doesn't send any Wabasca heavy oil production on this pipeline.

We'd also like to clarify your description of how Cenovus produces Wabasca heavy oil from our conventional oil operation at Pelican Lake in northern Alberta.

Cenovus employs an enhanced oil recovery technique that uses a mixture of water and polymer. This combination of water and polymer helps to push the heavy oil through the reservoir to production wells, where it's then brought to the surface. This is a different technology than the solvent aided process (SAP) being tested by Cenovus at one of our oil sands projects.

We currently have a pilot well using SAP at our Christina Lake steam-assisted gravity drainage operation. Butane, a naturally occurring hydrocarbon and the fuel used in disposable lighters, is mixed with steam to help thin the thick oil contained in the sand, allowing it to be pumped to surface.

Reg Curren
Senior Advisor, Media Relations
Cenovus Energy

Joyce DixonApr 4 2013 12:08 AM

It's despicable that semantics help these companies get away with what they have done and will do.

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