Stability of Depletion Chamber Edges in Oil Sands Recovery Processes

Many modifications to Steam-Assisted Gravity Drainage (SAGD) have been proposed to make the steam-based recovery process more efficient and profitable. A common approach is coinjection of additives with steam. There are two general classes of additives: first, solvents that dilute the bitumen leading to a higher mobility of oil phase and second, non-condensable gas (NCG) that provides an insulative effect in a reservoir to reduce heat loss and consequently raising the thermal efficiency. Solvents most used in oil sands processes are C3 to C7 solvents whereas NCGs typically consist of natural gas (methane) or carbon dioxide. Despite a lot of research on solvent and non-condensable gas additive processes, the underlying physical mechanisms of heat transfer, flow, and potential instability remain unresolved given the interplay of phase behavior, oil mobilization, heat transfer (conductive and convective), multiphase counter-current flow, and potential instabilities in steam-only, solvent-steam, and NCG-steam process are complex. This thesis documents research on these mechanisms and how they interact by using ultra-fine three-dimensional thermal reservoir models. The results of the analysis reveal that interfacial instabilities are observed in both pure-steam and steam-NCG (0.5 mol%) cases where the instabilities are evidenced by gas fingers that evolve above the top depletion chamber edge. The instability, triggered by dominant convective heat transfer, exhibits two types of fingers in the steam-only case: solution-gas fingers and thermally-stimulated oil viscous fingers, with consequently enhanced heat transfer rate. In the NCG-steam case, only solution-gas fingers are present, and the length scale of the fingers is smaller than that in the steam-only case. In the steam-solvent case, the presence of solvent tends to suppress the onset of the instabilities. This is due to the rich solvent band present at the chamber edge which causes the mitigated temperature gradient and consequently lower tendency for solution gas ex-solved from oil sands.

Name thesis:degree_name

Master of Science (MSc)

Discipline thesis:degree_discipline

Engineering – Chemical & Petroleum

Grantor dc:publisher.institution

Schulich School of Engineering

Year dc:date.issued

2021

Author dc:creator

• Zhou, Qian

Advisors dc:contributor.advisor

• Gates, Ian
• Benneker, Anne

Committee members dc:contributor.committeemember

• Sumon, Kazi
• Siegler, Hector De la

• oil viscous fingering
• instability;
• thermal-solvent recovery;
• steam-assisted gravity drainage;
• non-condensable gas
• thermal viscous fingers

Statement dc:rights

• University 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.

Language dc:language.iso

eng

DOI

http://dx.doi.org/10.11575/PRISM/38788

OAI identifier oai:identifier

oai:ucalgary.scholaris.ca:1880/113306