Potential for Hydrogen Generation during In Situ Combustion of Bitumen

Abstract

Abstract The volume of heavy oil and bitumen in Alberta, Canada is estimated to be about 1.7 trillion barrels. The majority of the produced heavy oil and bitumen in Alberta is converted in surface upgraders to synthetic crude oil, a crude oil with API gravity typically between 31 and 33°API, which in turn can be converted to fuel, lubricant, and petrochemical products in standard refineries. To upgrade bitumen requires hydrogen. In current practice, much of this hydrogen is generated from steam reforming of methane together with the water-gas shift reaction. This means that heavy oil and bitumen upgrading, as is currently done, requires huge amounts of natural gas to generate hydrogen. The potential for in situ generation of hydrogen by gasification of bitumen reservoirs offers an attractive alternative which can also have both economic and environmental benefits. For example, hydrogen generated from bitumen gasification can also be used for in situ upgrading as well as feedstock for ammonia and other chemicals. The water-gas shift reaction also generates carbon dioxide which could be potentially sequestered in an in situ gasification process so that emissions to the atmosphere are reduced. This study evaluates the effect of operating parameters such as temperature and pressure on the amount of hydrogen generated during in-situ combustion. Combustion of Athabasca bitumen incorporating thermal cracking, oxidation, and hydrogen generation and consumption reactions has been simulated. The results indicate ranges of temperature and pressure where bitumen combustion yields optimal hydrogen production. This research emphasizes the conditions at which hydrogen production can be maximized from the in-situ combustion of Athabasca bitumen. This technology provides a potentially clean method to produce fuel and feedstock material from bitumen, a relatively "dirty" fuel and feedstock oil, in addition to more energy efficient ways of extracting in-situ heavy oils.