Effect of Carbon Dioxide on Paraffinic Bitumen Froth Treatment: Asphaltene Precipitation from a Commercial Bitumen Froth Sample

[Image: see text] In this study, the effect of carbon dioxide in assisting paraffinic bitumen froth treatment was investigated. The work was divided into two parts, the effect of water addition on CO(2)-assisted asphaltene precipitation from a dry and clean bitumen sample by n-heptane and the effect of CO(2) injection to a mixture of n-heptane and a commercial bitumen froth sample. It was found that water addition to the dry and clean bitumen improved the beneficial effect of CO(2) on promoting asphaltene precipitation by n-heptane, where asphaltene precipitation increased by 2.5 percentage points (or 19%) with the presence of water and CO(2). The asphaltene precipitation enhancement may be due to chemical reactions between injected CO(2) and water in the formation of carbonic acid in the aqueous phase, which destabilized asphaltene. On the other hand, no improvement was detected under the control tests (N(2)). Similar results were observed in the case of CO(2) injection to paraffinic solvent (n-heptane) treatment of the commercial bitumen froth sample. The results indicated that when the commercial bitumen froth sample was mixed with n-heptane at a solvent/bitumen ratio of 1.08, the injection of 1.7 MPa CO(2) increased the amount of precipitated asphaltene from 10.0 ± 0.1% (without CO(2)) to 15.2 ± 0.2% (with 1.7 MPa CO(2)) at 90 °C, indicating a potential reduction of solvent usage by about 66%.