Investigating fracture network creation during hydraulic stimulation in enhanced geothermal systems
Abstract/Contents
- Abstract
- During hydraulic stimulation treatment in an enhanced geothermal (EGS) reservoir, it has been suggested that a complex fracture network including both preexisting natural fractures and newly formed fractures is created. In this stimulation mechanism, a fracture propagating from a preexisting natural fracture and the interaction of newly formed fractures and preexisting natural fractures play an important role in the creation of a fracture network. Analyzing the interaction between preexisting fractures and newly formed fractures during hydraulic stimulation is thus necessary to understand the creation of a fracture network. We approached to this research question with laboratory and numerical experiments for an EGS reservoir where large preexisting fractures dominate. Laboratory scale hydraulic fracturing experiments were conducted to investigate how a fracture network is created when a propagating hydraulic fracture and a preexisting fracture interact. The physics-based numerical model developed in this work was used to investigate fracture network creation from a small scale area including a small number of fractures to a reservoir scale with tens of fractures. We analyzed the geological factors that affect the fracture network patterns through the laboratory and numerical experiments. We observed that the stress state and preexisting fracture orientation affect the fracture propagation pattern in the laboratory experiments. The numerical analysis shows that the stress field induced by an upstream hydraulic fracture causes asymmetric distributions of normal and shear stresses along the preexisting fracture when they intersect, which resulted in initiation of a wing crack from the fracture tip on the side with larger angles. The numerical results also showed that the complexity of the created fracture network is affected by the fracture intersection angle, stress state, and injection rates. We reviewed past EGS projects and analyzed the stimulation mechanism during their hydraulic stimulation treatment. This study implies that stimulating a reservoir with poorly oriented preexisting fractures may result a complex and broad shaped fracture network, which would be beneficial for energy recovery.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2021; ©2021 |
| Publication date | 2021; 2021 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Abe, Ayaka |
|---|---|
| Degree supervisor | Horne, Roland N |
| Thesis advisor | Horne, Roland N |
| Thesis advisor | Kovscek, Anthony R. (Anthony Robert) |
| Thesis advisor | Tchelepi, Hamdi |
| Degree committee member | Kovscek, Anthony R. (Anthony Robert) |
| Degree committee member | Tchelepi, Hamdi |
| Associated with | Stanford University, Department of Energy Resources Engineering |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Ayaka Abe. |
|---|---|
| Note | Submitted to the Department of Energy Resources Engineering. |
| Thesis | Thesis Ph.D. Stanford University 2021. |
| Location | https://purl.stanford.edu/bg829nj2270 |
Access conditions
- Copyright
- © 2021 by Ayaka Abe
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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