Incorporating some heat injection along with the solvent injection appears to be the most viable option for improving the drainage rate of VAPEX in extra-heavy oil formations. The obvious question then concerns the magnitude of temperature increase needed to make the drainage rate economical. The objective of this work was to examine the effect of temperature on VAPEX performance.
VAPEX experiments under different operating conditions were conducted in a high-pressure physical model. Physical model was packed with 250 Darcy sand and saturated with Athabasca bitumen (Mackay River oil). Injecting propane at 0.817 MPa, temperatures from 40 to 60ºC were tested to investigate possible improvement to oil production rates. Experimental results were numerically simulated with a commercial compositional simulator, Computer Modelling Group's (CMG) GEM. CMG's WinProp module, along with available experimental data, was employed to model the phase behavior and properties of the propane / Athabasca bitumen system.
By history matching the experimental production data, results were extended to wider ranges of temperature and VAPEX performance at elevated temperatures was investigated. According to the results, substantial improvement in the performance of VAPEX in reservoirs containing this type of oil would require increasing the reservoir temperature above 60ºC.