In situ combustion is a thermal recovery method with a high potential forrecovering the vast hydrocarbon reserves located in the Athabasca Oil Sands. Inorder to understand and optimize the combustion process, fireflooding has beenthe focus of laboratory investigations by the In Situ Combustion Research Groupat the University of Calgary. Over a 10-year period, 47 normal air laboratorycombustion tube tests were performed on Athabasca Oil Sands core. These testsinvestigated a range of pressures, injected air fluxes, injected water to airratios and core packing techniques. This paper summarizes an in depth analysisof these tests. and identifies trends common to the entire data set.

The most important results of these investigations were the confirmation of anegative temperature gradient region between 350 and 450 °C wherein stablecombustion did not occur, a well-defined relationship between combustiontemperature and levels of produced carbon dioxide, and a numerical correlationbetween the viscosity and asphaltenes content of the produced bitumen. Thesefindings were consistent with those observed using much smaller reactors andfor other reservoirs. This study suggests that wet in situ combustion may besuccessfully applied to the Athabasca Oil Sands reservoir so long as sufficientbitumen mobility can be maintained.


The Athabasca Oil Sands reservoir of northeastern Alberta which containsapproximately 151 × 109 m3 (950 × 109 barrels)of bitumen, is one of the world's largest reserves of accessible hydrocarbons.Although approximately 10 percent of the reservoir can be economicallyrecovered by surface mining, the remainder of the bitumen must be removed fromthe sand by in situ recovery techniques1.

In situ combustion is an enhanced recovery technique with great potential forrecovering the vast hydrocarbon reserves of the Athabasca Oil Sands. Althoughthis method offers a very high theoretical efficiency and many advantages overother processes, it has had limited success in the field, primarily because ofa lack of understanding of how combustion actually works. The In SituCombustion Research Group at the University of Calgary has been investigatingthe combustion process under the direction of Drs. D.W. Bennion, J.K. Donnellyand R.G. Moore since its inception in 1972. Since that time, the group hasperformed 270 combustion tube tests on cores from over 50 reservoirs worldwide, as well as associated kinetics research on thermal cracking, low- andhigh-temperature oxidation and ignition processes,

This study focusses on 47 in situ combustion tube tests which were performedbetween 1976 and 1986 at the University of Calgary on core materials from the Athabasca Oil Sands reservoir. The tests, which all used normal air (21 percentoxygen) as the oxidant, were performed at a variety of operating conditions ontwo combustion tube systems. Eight of the early tests were performed for the Government of Canada's Department of Energy, Mines and Resources (EMR), whilethe remainder were carried out under research contracts with the Alberta OilSands Technology and Research Authority (AOSTRA). The tests were not consideredas a thorough parametric study, but were carried out in order to understand theunderlying mechanisms controlling dry and wet in situ combustion and todetermine the potential forapplying fireflooding to the Athabasca Oil Sandsreservoir. Thus, the run conditions were varied as necessary to pursuepromising avenues of investigation. However, because of the large number oftests performed and their good repeatability, this series of tests has become abenchm

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