Asphaltene Precipitation From Cold Lake and Athabasca Bitumens

The onset of asphaitene precipitation from Cold Lake and Athabasca bitumens was studied using a heat transfer technique. The onset for these two types of bitumen was at a n-heptane to bitumen volume ratio of 1.4 to 1.7. Since it is important to suppress the onset of precipitation, a number of additives (aromatics; hydrogen donor solvents, solvents with the heteroatoms nitrogen, sulphur, and oxygen; and surfactants) were tested for their ability to delay the onset of asphaitene precipitation from Cold Lake bitumen. Phenanthrene, an aromatic, and the surfactant nonyl-phenol were found to be most effective. Cold Lake bitumen maltenes were found to be as effective as the aromatic chemical additives in delaying the onset of asphaitene precipitation. As the maltenes fraction contains saturates, the resins fraction alone should be even more effective at delaying precipitation.