Yarranton, Harvey W.Shaygan, Kaveh2024-04-302024-04-302024-04-23Shaygan, K. (2024). Investigation of gravity drainage of heavy oil into a flowing solvent layer in porous media (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/11850610.11575/PRISM/43348The condensing solvent bitumen recovery process is a promising alternative to steam-assisted processes in terms of greenhouse gas emissions and energy consumption reduction. In this process, the solvent vapor injected into the reservoir 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. The details of the underlying physical mechanisms of this process (gravity drainage and mass transfer) are not fully understood, and predictive models are lacking. This thesis focuses on the little-investigated role of solvent flow rate, permeability and irreducible water saturation in condensing solvent processes. In order to better understand and represent the mechanisms controlling the process, a 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. The experiments were performed with silica sands and glass beads with and without irreducible water saturation. Toluene volumetric flow rates between 0.5 to 15 cm³/min and permeabilities within the range of 47 to 254 D were considered. Bitumen and solvent recoveries were measured over time and the change in bitumen profile was tracked with a camera. The key mechanisms of the process were verified to be diffusion of bitumen into solvent through convective mass transfer and convective flow of the resulting mixture in the drainage layer by gravity. The high dilution (high flow rate) data were predicted with an analytical model obtained from the solution of Fick’s second law of diffusion for the effective mass transfer of bitumen into the flowing drainage layer according to Darcy’s law. The full range of data was matched with a numerical model based on convective mass transfer of bitumen into the drainage layer using a correlated convective mass transfer coefficient derived from effective molecular diffusivity and Darcy flow. The correlation has only one adjustable parameter which was constant for steady-state mass transfer in the semi-infinite acting regime. Neither model required mechanical dispersion even in presence of irreducible water. A square root dependence of mass flux versus permeability was observed, consistent with molecular diffusion with no mechanical dispersion.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Gravity drainageDiffusionConvective mass transferHeavy oilSolvent-based recoveryEngineering--Petroleumdoctoral thesis