Summary
Steam/solvent coinjection has been studied as a potential method to improve the efficiency of conventional steam-assisted gravity drainage (SAGD) for bitumen recovery. This research is part of an experimental program for phase behavior of Athabasca-bitumen/solvent mixtures.
This paper presents a new set of experimental data for phase equilibrium, viscosity, density, and asphaltene precipitation for 11 mixtures of Athabasca bitumen with n-hexane and 10 mixtures of the same bitumen with n-octane. Phase-boundary measurements were conducted at temperatures up to 160°C and pressures up to 10 MPa. The bitumen sample used in this research was studied in our previous research, in which the same bitumen was not effectively diluted by n-butane because of the coexistence of a butane-rich liquid with a bitumen-rich liquid phase.
In this research, the liquid/liquid separation of hydrocarbons was not observed for n-hexane/bitumen (HB) and n-octane/bitumen (OB) mixtures for the range of temperatures and pressures tested, even at solvent concentrations higher than 90 mol%. This observation indicates that the amount of solvent available near the edge of a steam chamber is expected to be entirely used for bitumen dilution beyond the chamber edge in coinjection of steam with heavier hydrocarbon solvents, such as n-hexane and n-octane.
Experiments for asphaltene precipitation at atmospheric pressure showed a larger amount of precipitates with n-hexane than with n-octane at a given solvent concentration higher than 50 wt%. For solvent concentrations less than 50 wt%, no asphaltene precipitation was observed for both solvents with the bitumen sample tested in this research.
Effect of Thermal and Hydro-Catalytic Treatment on the Molecular Chemistry of Narrow Fractions of Athabasca Bitumen Pitch
