Investigation of Solvent-Assisted Gravity Drainage in a Packed Hele-Shaw Cell with Liquid Toluene over Bitumen

Abstract

The condensing solvent process is a heavy oil (or bitumen) recovery method where the injected vapor solvent condenses when it contacts the colder bitumen and the bitumen diffuses into the condensed liquid. The process has been piloted, but field implementation is impeded by the absence of a reliable model to upscale laboratory measurements to the field scale. In order to better understand and represent the mechanisms controlling the process, a glass-bead-packed Hele-Shaw type apparatus was partially filled with bitumen with a sloped interface, and liquid toluene was flowed on top of the bitumen layer at a fixed flow rate. Bitumen and solvent recoveries were measured over time, and the change in the bitumen profile was tracked with a camera. The key mechanisms of the process were verified to be the diffusion of bitumen into solvent through convective mass transfer and convective flow of the resulting mixture in the drainage layer by gravity. An approximate analytical solution was derived for dilute conditions (high solvent flow rates) and used to identify the transition from a finite to a semi-infinite mass transfer boundary condition in the drainage layer. A numerical model was fitted to the experimental data, and a correlation was established for the convective mass transfer coefficient of bitumen into the solvent in porous media. The correlation has only one adjustable parameter which was constant for steady-state mass transfer in the semi-infinite acting regime.