Development of Enhanced Geothermal Systems (EGS) in Northern Alberta Open Access
- Other title
Pressure dependent fracture permeability
Particle Flow Code
Grain based modeling
complex fracture development
geothermal energy for oil sands processing
enhanced geothermal systems (EGS)
- Type of item
- Degree grantor
University of Alberta
- Author or creator
- Supervisor and department
Zimmermann, Günter (German Research Centre for Geosciences, Potsdam, Germany)
Babadagli, Tayfun (Civil and Environmental Engineering)
- Examining committee member and department
Okuno, Ryosuke (Civil and Environmental Engineering)
Apel, Derek (Civil and Environmental Engineering)
Babadagli, Tayfun (Civil and Environmental Engineering)
Kuru, Ergun (Civil and Environmental Engineering)
Schmitt, Doug (Physics)
Department of Civil and Environmental Engineering
- Date accepted
- Graduation date
Doctor of Philosophy
- Degree level
In the province of Alberta a huge amount of energy is needed for diverse applications. Specifically, the demand for heat is limited to a few locations such as the oil sands operation regions and metropolitan areas. Oil sands processing facilities near Fort McMurray and direct heat provision for different applications in the City of Edmonton are two of these major heat consumers in the province. Currently, this heat is mainly supplied by burning natural gas with significant greenhouse gas (GHG) emissions.
Geothermal energy may be an alternative heat source for these applications. While the required temperatures are reached within the sedimentary basin underneath Edmonton, wells need to be drilled deep into the granitic basement in the Fort McMurray area. Whereas high enough temperatures can be reached with sufficiently deep wells, in both cases the permeability in these deep sedimentary and granitic rocks is insufficient to produce large enough amounts of hot water.
Therefore, these rocks need to be hydraulically stimulated to improve the productivity of the wells without causing premature breakthrough of cold fluid from the injection wells. Such an enhanced geothermal system (EGS) is currently the only method that has the potential to provide heat from the earth’s crust for the investigated applications. However, so far, no economically operating EGS could be developed in granitic basement rocks, which shows that earlier reservoir engineering concepts were not sufficient and parameters and processes governing the development and operation of EGS are very complex and not well enough understood.
Using a variety of numerical methods, this thesis investigates whether EGS can be an alternative low GHG emission heat source for oil sands processing in Fort McMurray and direct heating applications in Edmonton, and how these systems should be designed to make them technically feasible and economically competitive.
It was found that the deployment of EGS can significantly reduce GHG emissions and save valuable gas resources at similar costs to burning natural gas only if the fracture network is optimally engineered. The reservoir modeling results suggested that the development of well-connected complex fracture networks between horizontal or deviated wells by multiple stimulation treatments is the most promising concept to achieve these goals. Therefore, the hydraulic stimulation process was studied numerically at the micro and giga scale and based on these results a reservoir engineering concept was proposed for the sedimentary rocks in the Edmonton area and the granitic basement rocks in Fort McMurray. Also, natural factors were identified that promote complex fracture network development in low permeability granitic basement rocks.
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
- Citation for previous publication
Hofmann, H., Babadagli, T., and Zimmermann, G. (2012). Hydraulic fracturing scenarios for low temperature EGS heat generation from the Precambrian basement in Northern Alberta. GRC Transactions, 36:459-467.Hofmann, H., Weides, S., Babadagli, T., Zimmermann, G., Moeck, I., Majorowicz, J., and Unsworth, M. (2014). Potential for enhanced geothermal systems in Alberta, Canada. Energy, 69:578-591.Hofmann, H., Babadagli, T., and Zimmermann, G. (2014). Hot water generation for oil sands processing from enhanced geothermal systems: process simulation for different hydraulic fracturing scenarios, Applied Energy, 113:524-547.Hofmann, H., Babadagli, T., and Zimmermann, G. (2014). Numerical simulation of complex fracture network development by hydraulic fracturing in naturally fractured ultratight formations. Journal of Energy Resources Technology, 136:042907 (9 pages).Hofmann, H., Babadagli, T., Yoon, J.S., Zang, A., and Zimmermann, G. (2015). A grain-based modeling study of mineralogical factors affecting strength, elastic behaviour and micro fracture development during compression tests in granites. Submitted to Engineering Fracture Mechanics (under review).Hofmann, H., Babadagli, T., and Zimmermann, G. (2015). A grain based modeling study of fracture branching during compression tests in granites. Accepted for publication in International Journal of Rock Mechanics and Mining Sciences.Hofmann, H., Blöcher, G., Milsch, H., Babadagli, T., and Zimmermann, G. (2015). Continuous measurement of time and pressure dependent fracture permeability of aligned and displaced tensile fractures in granitic rock during cyclic loading. Submitted to Geophysical Journal International (under review).Hofmann, H., Babadagli, T., Yoon, J.S., and Zimmermann, G. (2015). A hybrid discrete/finite element modeling study of complex hydraulic fracture development for enhanced geothermal systems (EGS) in granitic basements. Submitted to International Journal of Fracture (under review).
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