An Experimental Study of Multiphase Behavior for Athabasca-Bitumen/Alkane-Solvent Mixtures

  • Author / Creator
    Gao, Jianyi
  • Steam-solvent coinjection has been studied and pilot-tested as a potential method to improve steam-assisted gravity drainage for bitumen recovery. Reliable design of coinjection requires reliable PVT data for bitumen/solvent/water mixtures, which are scarce and fragmentary in the literature. In this study, a new set of pressure-volume-temperature and multiphase data were obtained for Athabasca-bitumen/solvent mixtures at pressures up to 10 MPa and temperatures up to 160C. The solvents used are n-butane, n-hexane, and n-octane. Also, experiments were conducted for one Athabasca-bitumen/n-butane/water mixture. A single equation-of-state model was developed to correlate all experimental data obtained, and used to interpret complex multiphase behavior observed for the highly size-asymmetric polar mixtures. An n-butane/bitumen mixture at a high concentration of n-butane (97.24 mol%) exhibited liquid-liquid separation of hydrocarbons, consisting of the bitumen-rich and butane-rich liquid phases, at temperatures from 80C to 160C at operating pressures. Addition of water to this complex mixture resulted in four equilibrium phases: the vapor, aqueous, bitumen-rich liquid, and butane-rich liquid phases. This is the first time four coexisting phases were experimentally confirmed for the Athabasca-bitumen/solvent/water system. The liquid-liquid separation of hydrocarbons indicates that coinjection of steam with highly volatile solvents, such as n-butane, for Athabasca bitumen may result in less effective dilution of bitumen, even when the solvent sufficiently accumulates near the edge of a steam chamber. Unlike n-butane, n-hexane and n-octane did not yield the liquid-liquid immiscibility with Athabasca bitumen in this research. Also, results for the n-hexane/bitumen and n-octane/bitumen mixtures indicate that n-hexane is a more effective solvent for reducing bitumen viscosity than n-octane at the same solvent-weight fraction in mixtures. However, n-hexane resulted in more asphaltene-precipitation yields than n-octane when mixed with Athabasca bitumen at ambient pressure.

  • Subjects / Keywords
  • Graduation date
    Fall 2016
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.