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Beyond Viscosity—How Density, Vibration and Interfacial Tension Affect Solvent Aided Bitumen Production
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- Author / Creator
- Stewart, Robert A
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Bitumen and heavy oil comprise a significant percentage of proven oil reserves globally. The environmental impacts of producing these resources with current technologies is a concern for environmentalists, oil producing companies, resource rich jurisdictions and society at large. Dilution of the viscous oil with solvents could permit the production of these reserves with lower greenhouse gas emissions than is achieved using current thermal methods where viscosity is reduced by heating. Solvent injection has yet to be implemented as the production method of choice and this suggests that there is significant residual technological uncertainty. Two orders of magnitude disagreements between predicted production rates, based largely on analogies with thermal production methods, and rates extrapolated from laboratory and pilot plant experimental results contribute to this uncertainty, and underscore fundamental and process knowledge gaps between laboratory experiments and field application. This thesis addresses a number of potential impacts of adding solvents to bitumen production processes, whether pilot plants or operating facilities that have been under represented in the publically available literature to date. The addition of solvents to the production environment changes fluid properties beyond the desired viscosity reduction. Changes in fluid density and interfacial tension impact the force balance in reservoirs and laboratory apparatus. External factors such as ambient vibration can also affect production outcomes. The impacts of properties and external environmental conditions are addressed in this work through the systematic application of dimensionless group comparisons and scaling analysis benchmarked with experiments. The change in density of the hydrocarbon with the addition of solvent relative to connate water density is addressed. Conditions where the hydrocarbon phase density changes from more to less dense than that of water are identified. Implications for the production of bitumen are discussed. The impacts of vibration are addressed. An experimental apparatus is described and the predominance of impacts arising from bubble formation and movement in vibrating unconsolidated porous media systems are illustrated using Ultra Violet (UV) fluorescent imaging. The apparatus, experimental outcomes and scaling analysis are expected to apply to diverse processes from packed catalyst beds in process reactors to geologic carbon dioxide sequestration in addition to bitumen and heavy oil production. Dimensionless group analysis is used to compare and contrast solvent and thermal production environments. Bond number value differences suggest that interfacial tension plays a larger role in solvent assisted production environments than previously recognized. This insight, along with support from Prandtl and Schmidt number values, support a new but as yet unproven discrete flow mechanism “sloughing at the bitumen solvent interface” that controls the kinetics of solvent assisted bitumen production. Outcomes from this work are relevant to industrial and academic researchers alike in the target application. They will influence experimental design, apparatus construction and operation, and hypothesis testing as researchers attempt to reduce environmental impacts of heavy hydrocarbon and bitumen production. Impacts in related fields involving complex fluid motion in porous media are also anticipated. The ongoing relevance and importance of scaling laws and dimensional analysis is underscored.
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- Graduation date
- Fall 2016
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.