Abstract
Development of a supercritical geothermal system at great depth has been proposed to enhance geothermal heat extraction. Hydraulic fracturing at great depth may induce mixed-mode (opening and shear mode) crack propagation due to high tectonic stress. The purpose of this study is to predict the crack growth behavior under high tectonic stress conditions corresponding to great depth. This study presents a finite element model for the analysis of hydraulic fracturing, taking account of mixed-mode fracture. In the finite element model, an embedded crack element is employed to represent arbitrary crack geometry due to mixed-mode crack propagation. A mixed-mode failure criterion, including a fracture process zone model, is incorporated into the embedded crack model as a crack constitutive law. The growth behavior of hydraulically induced cracks is analyzed. The numerical results demonstrate that the crack growth behavior, i.e. the mode of crack propagation, depends on depth. Under typical tectonic stress conditions, the crack growth mode is dominated by opening mode above 4 - 5km depth. This result suggests that the current target of supercritical geothermal reservoirs may be formed mainly under opening mode.
| Original language | English |
|---|---|
| Pages (from-to) | 297-302 |
| Number of pages | 6 |
| Journal | Transactions - Geothermal Resources Council |
| Publication status | Published - 2002 Dec 1 |
| Event | Geothermal Resources Council: 2002 Annual Meeting - Reno, NV, United States Duration: 2002 Sep 22 → 2002 Sep 25 |
Keywords
- Cohesive crack model
- Deep-seated geothermal reservoir
- Embedded crack element
- Finite element method
- Hydraulic fracturing
- Mixed-mode fracture
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Energy Engineering and Power Technology
- Geophysics