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


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 Crudemoniter.ca 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.

About the Authors

Anthony Swift

Director, Canada Project, International program

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