A solvent-assisted gravity drainage process (Vapex) for recovery of heavy oil or bitumen offers high recoveries and promising rates of oil production. In order to predict process performance, data on solvent-oil solubility and on the viscosity of solvent-oil mixtures must be obtained.
The solubility of selected gasses in Lloydminster Aberfeldy oil and in a Cold Lake oil was measured. The gasses used were: CH4, C2H6, C3H8 and CO2. Measurements were done at reservoir temperature. The data were regressed using the Peng-Robinson equation of state, which was used to generate k-values expressing the solubility of the gas-oil systems. Regressing the Peng-Robinson equation to the measured data generated interaction coefficients for the systems measured. These coefficients were used with the equation to generate k-value or solubility tables at other conditions. Measured viscosity data were used to confirm the usefulness of the Puttagunta viscosity correlation for propane-based heavy oil systems. The work confirmed the formation of two liquid phases in the oil-propane system at high solvent loading. The measurements also confirmed the large viscosity reductions available (100:1 – 200:1) by saturating oil with light hydrocarbons. A viscosity increase in one oil-propane system was observed at high solvent loading, suggesting possible asphaltene precipitation and/or deposition on the walls of the capillary viscometer tube.
These observations confirmed the need to study phase behaviour and asphaltene deposition in the oils at high solvent loading, as well as obtaining solubility and viscosity measurements. The data have been used to perform numerical simulations of Vapex and other solvent-based processes, and to perform predictions of field process performance.