Two fundamental upgrading processes are presently employed to prepare heavy oil and natural bitumen for transportation and refining to finished products. These processes are carbon rejection and hydrogen addition. Each process improves the hydrogen-to-carbon ratio but by following different paths, Carbon rejection, such as Flexi cocking, yields a large quantity of low Btu gas at the expense of produced liquids, a large amount of petroleum coke, and therefore moderate conversion at low pressure. A hydrogen addition process, such as VEBA-Combo-Cracking (VCC) heats the raw material under pressure, the resulting gas begin combined with added hydrogen to maximize liquids yield through high conversion. High conversion carries an economic penalty because of the cost of the added hydrogen and the high pressures required. The choice, therefore, is economic, being related to demand for the resulting products.

The yield of upgraded oil (synthetic crude oil) from the natural bitumen. Based on the Alberta experience, varies with the technology employed, the extent of natural gas liquids recovery, and the degree of residue upgrading. The Canadian company Suncor uses delayed coking for a yield of 0.81, whereas Sync rude (another Canadian company) obtains a yield of 0.85 through fluid coking combined with hydrocracking. The expected yield for the Albina sands sub-project of the Shell/Chevron/Western Athabasca Oil Sands Project is 0.90, using hydrocracking.