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Development of Enhanced Geothermal Systems (EGS) in Northern Alberta

  • Author / Creator
    Hofmann, Hannes

  • 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.

  • Subjects / Keywords
  • Graduation date
    Fall 2015
  • Type of Item
    Thesis
  • Degree
    Doctor of Philosophy
  • DOI
    https://doi.org/10.7939/R3445HQ00
  • 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.