Hannes Hofmann

PhD (2015)

Current position: GFZ

Research topic: Development of Enhanced Geothermal Systems (EGS) in Northern Alberta

Thesis

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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.

 

Publications:

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1. Hofmann, H., Babadagli, T. and Zimmermann, G.: “Conception and Simulation of Hydraulic Fracturing Treatments for the development of Enhanced Geothermal Systems (EGS) in the Precambrian Basement Rocks in Northern Alberta,” presented at the 4th HAI (Helmholtz-Alberta Initiative)-E&E Science Forum, Edmonton, Sept., 29, 2014.

2. Hofmann, H., Babadagli, T. and Zimmermann, G.: “Hot Water Generation for Oilsands Processing from Hot-Dry-Rocks: Process Simulation for Different Hydraulic Fracturing Scenarios,” 2nd HAI Science Forum, Potsdam, Germany, Sept. 10-11, 2012.

3. Hofmann, H., Babadagli, T. and Zimmermann, G.: “Conception and Simulation of Hydraulic Fracturing Treatments for the development of Enhanced Geothermal Systems (EGS) in the Precambrian Basement Rocks in Northern Alberta,” presented at 3rd Annual Meeting of Helmholtz-Alberta Initiative (HAI), Edmonton, May 10-11, 2012.

4. Zimmermann, G., Hofmann, H., Babadagli, T., Yoon, J., Zang, A., Urpi, L., Blöcher, G., Hassanzadegan, A. and Huenges, E.: “Multi-fracturing and cyclic hydraulic stimulation scenarios to develop Enhanced Geothermal Systems - Feasibility and mitigation strategies to reduce seismic risk,” 2015 World Geothermal Congress, 19-25 Apr., Australia–New Zealand.

5. Hofmann, H., Yoon, J., Zang, A., Urpi, L., Blöcher, G., Zimmermann, G. and Babadagli, T.: “A New Hybrid Simulation Approach to Evaluate the Efficiency of Hydraulic Stimulation Treatments,” 2015 World Geothermal Congress, 19-25 Apr., Australia–New Zealand.

6. Majorowicz, J., Hofmann, H. and Babadagli, T.: “Deep Geothermal Heat Storage under Oilsands: Can We Use it to Help Oilsands Industry? New EGS Concept Proposed,” 37th Annual Meeting of Geothermal Resources Council (GRC), Las Vegas, NV, Sept. 29-Oct. 2, 2013.

7. Hofmann, H., Weides, S., Babadagli, T., Zimmermann, G., Moeck, I. Majorowicz, J. and Unsworth, M.: “Integrated Reservoir Modeling for Enhanced Geothermal Energy Systems in Central Alberta, Canada,” Stanford Geothermal Workshop, Feb. 11-13, 2013, Palo Alto, CA.

8. Hofmann, H., Babadagli, T., and Zimmermann, G.: “Numerical Simulation of Complex Fracture Network Development by Hydraulic Fracturing in Naturally Fractured Ultratight Formations,” 32nd Int. Conf. on Ocean, Offshore and Arctic Engineering, Nantes, France, June 9-14, 2013.

9. Hofmann, H., Babadagli, T. and Zimmermann, G.: “Hydraulic Fracturing Scenarios for Low Temperature EGS Heat Generation from the Precambrian Basement in Northern Alberta,” 36th Annual Meeting of Geothermal Resources Council (GRC), Reno, NV, Sept. 30-Oct. 3, 2012, pp. 17. Won the GRC Best Presentation Award "in recognition of quality of content and presentation at the EGS 6 session".

10. Hofmann, H., Babadagli, T., Yoon, J., Blocher, G., and Zimmermann, G.: “A Hybrid Discrete/Finite Element Modeling Study of Complex Hydraulic Fracture Development for Enhanced Geothermal Systems (EGS) in Granitic Basements,” accepted for publication in Geothermics, 2016.

11. Hofmann, H., Blocher, G., Milsch, H., Babadagli, T., and Zimmermann, G.: “Transmissivity of aligned and displaced tensile fractures in granitic rocks during cyclic loading,” Int. J. of Rock Mech. & Min. Sci., vol. 87, 69-84, Sept. 2016.

12. Hofmann, H., Babadagli, T. and Zimmermann, G.: “A Grain Based Modeling Study of Fracture Branching during Compression Tests in Granites,” accepted for publication in Int. J. of Rock Mech. and Min. Sci., 2015.

13. Hofmann, H., Babadagli, T., Yoon, J., Zang, A., and Zimmermann, G.: “A Grain Based Modeling Study of Mineralogical Factors Affecting Strength, Elastic Behaviour and Micro Fracture Development during Compression Tests in Granites,” Engineering Fracture Mechanics, vol. 147, 261-275, 2015.

14. Hofmann, H., Babadagli, T., and Zimmermann, G.: “Numerical Simulation of Complex Fracture Network Development by Hydraulic Fracturing in Naturally Fractured Ultratight Formations,” J. of Energy Resources Technology, vol. 136, 042907 / 1-9, Dec. 2014.

15. Hofmann, H., Weides, S., Babadagli, T., Zimmermann, G., Moeck, I. Majorowicz, J. and Unsworth, M.: “Potential for Enhanced Geothermal Systems in Alberta, Canada,” Energy, vol. 69, 578-591, 2014.

16. Hofmann, H., Babadagli, T., and Zimmermann, G.: “Hot Water Generation for Oil Sands Processing from Enhanced Geothermal Systems: Process Simulation for Different Hydraulic Fracturing Scenarios,” Applied Energy, vol. 113, 524-547, 2014.

17. Majorowicz, J., Hofmann, H. and Babadagli, T.: “Deep Geothermal Heat Storage under Oilsands: Can We Use it to Help Oilsands Industry? New EGS Concept Proposed,” GRC Transactions, vol. 37, 173-178, 2013.

18. Hofmann, H., Babadagli, T. and Zimmermann, G.: “Hydraulic Fracturing Scenarios for Low Temperature EGS Heat Generation from the Precambrian Basement in Northern Alberta,” GRC Transactions, vol. 36, 459-467, 2012.

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