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Colorado School of Mines

1. Permata, Ilham. Enhanced geothermal system (EGS) well stimulation design and simulation using DFN-based model : Newberry EGS case study.

Degree: MS(M.S.), Petroleum Engineering, 2019, Colorado School of Mines

A conceptual model of the Newberry EGS (Enhanced Geothermal System) project stimulation program for well NWG 55-29 has been developed. A discrete fracture network (DFN) model is embedded in the simulation to investigate effect of in situ stress state and natural fractures or faults properties. The local in situ stress information has been revisited and a new interpretation is proposed. Simulation results using the conceptual model are compared to a case of previously published stress information. To revisit the stress determination, compressive failure around a wellbore has been analyzed and different modes of breakouts were distinguished. Incorporating temperature change, a simple compressive failure model based on Mohr-Coulomb failure criterion for inclined wellbores has been developed. The model has been first used to perceive compressive failure profile when breakouts and tensile wall fractures simultaneously occurred at a wellbore from a well at Visund Field in the North Sea. The model illustrates distinct profiles at the direction of breakouts and tensile wall fractures. Further, it is also applied to well GPK2 at the Soultz geothermal field in France, where thermally induced or mode-X breakout has been observed. Different modes of compressive wellbore failure are observed, B-mode for conventional breakout and X-mode for breakout at the opposite side as compressive failure happening due to small tensile cracks. This distinct profile was then used to analyze the compressive failure profile for the NWG 55-29 well in Newberry EGS. Eventually, mode-X breakout is observed, indicating the direction of maximum horizontal stress, instead of minimum horizontal stress as previously studied. This finding is consistent with image log observation of nearby well and regional shear wave evaluation. The simulation is conducted using CFRAC simulator. Based on microseismic distribution and bottomhole pressure data, the simulation case with current stress determination is more consistent. It is also suggested that hydroshearing is not enough to enhance permeability in not-well-oriented natural fracture distribution. Though this is not a desired case for thermal extraction, better permeability enhancement could be achieved by injection pressure higher than the minimum horizontal stress. This study demonstrated that the simple failure model could be utilized in accordance with breakout observations and how prior stress determination and fracture characterization could significantly affect stimulation design and reservoir development strategy. Advisors/Committee Members: Tutuncu, Azra (advisor), Miskimins, Jennifer L. (committee member), Wu, Yu-Shu (committee member).

Subjects/Keywords: EGS; Geothermal; Thermally-induced breakout; Failure model; Breakout; Newberry EGS

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Permata, I. (2019). Enhanced geothermal system (EGS) well stimulation design and simulation using DFN-based model : Newberry EGS case study. (Masters Thesis). Colorado School of Mines. Retrieved from http://hdl.handle.net/11124/173092

Chicago Manual of Style (16th Edition):

Permata, Ilham. “Enhanced geothermal system (EGS) well stimulation design and simulation using DFN-based model : Newberry EGS case study.” 2019. Masters Thesis, Colorado School of Mines. Accessed August 24, 2019. http://hdl.handle.net/11124/173092.

MLA Handbook (7th Edition):

Permata, Ilham. “Enhanced geothermal system (EGS) well stimulation design and simulation using DFN-based model : Newberry EGS case study.” 2019. Web. 24 Aug 2019.

Vancouver:

Permata I. Enhanced geothermal system (EGS) well stimulation design and simulation using DFN-based model : Newberry EGS case study. [Internet] [Masters thesis]. Colorado School of Mines; 2019. [cited 2019 Aug 24]. Available from: http://hdl.handle.net/11124/173092.

Council of Science Editors:

Permata I. Enhanced geothermal system (EGS) well stimulation design and simulation using DFN-based model : Newberry EGS case study. [Masters Thesis]. Colorado School of Mines; 2019. Available from: http://hdl.handle.net/11124/173092

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