Fluid pressure drops during stimulation of segmented faults in deep geothermal reservoirs
Abstract Hydraulic stimulation treatments required to produce deep geothermal reservoirs present the risk of generating induced seismicity. Understanding the processes that operate during the stimulation phase is critical for minimising and preventing the uncertainties associated with the exploitati...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2018-11-01
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| Series: | Geothermal Energy |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s40517-018-0110-7 |
| _version_ | 1818516774277087232 |
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| author | Guillem Piris Albert Griera Enrique Gomez-Rivas Ignasi Herms Mark W. McClure Jack H. Norbeck |
| author_facet | Guillem Piris Albert Griera Enrique Gomez-Rivas Ignasi Herms Mark W. McClure Jack H. Norbeck |
| author_sort | Guillem Piris |
| collection | DOAJ |
| description | Abstract Hydraulic stimulation treatments required to produce deep geothermal reservoirs present the risk of generating induced seismicity. Understanding the processes that operate during the stimulation phase is critical for minimising and preventing the uncertainties associated with the exploitation of these reservoirs. It is especially important to understand how the phenomenon of induced seismicity is related to the pressurisation of networks of discrete fractures. In this study, we use the numerical simulator CFRAC to analyse pressure drops commonly observed during stimulation of deep geothermal wells. We develop a conceptual model of a fractured geothermal reservoir to analyse the conditions required to produce pressure drops and their consequences on the evolution of seismicity, fluid pressure, and fracture permeability throughout the system. For this, we combine two fracture sets, one able to be stimulated by shear-mode fracturing and another one able to be stimulated by opening-mode fracturing. With this combination, the pressure drop can be triggered by a seismic event in the shear-stimulated fracture that is hydraulically connected with an opening-mode fracture. Our results indicate that pressure drops are not produced by the new volume created by shear dilatancy, but by the opening of the conjugated tensile fractures. Finally, our results reveal that natural fracture/splay fracture interaction can potentially explain the observed pressure drops at the Rittershoffen geothermal site. |
| first_indexed | 2024-12-11T00:47:00Z |
| format | Article |
| id | doaj.art-a438d2718e9b45cb9725cc3f795c269e |
| institution | Directory Open Access Journal |
| issn | 2195-9706 |
| language | English |
| last_indexed | 2024-12-11T00:47:00Z |
| publishDate | 2018-11-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Geothermal Energy |
| spelling | doaj.art-a438d2718e9b45cb9725cc3f795c269e2022-12-22T01:26:45ZengSpringerOpenGeothermal Energy2195-97062018-11-016112110.1186/s40517-018-0110-7Fluid pressure drops during stimulation of segmented faults in deep geothermal reservoirsGuillem Piris0Albert Griera1Enrique Gomez-Rivas2Ignasi Herms3Mark W. McClure4Jack H. Norbeck5Departament de Geologia, Universitat Autònoma de BarcelonaDepartament de Geologia, Universitat Autònoma de BarcelonaDepartament de Mineralogía, Petrología i Geología Aplicada, Universitat de BarcelonaInstitut Cartogràfic i Geològic de Catalunya (ICGC)ResFrac CorporationDepartment of Energy Resources Engineering, Stanford UniversityAbstract Hydraulic stimulation treatments required to produce deep geothermal reservoirs present the risk of generating induced seismicity. Understanding the processes that operate during the stimulation phase is critical for minimising and preventing the uncertainties associated with the exploitation of these reservoirs. It is especially important to understand how the phenomenon of induced seismicity is related to the pressurisation of networks of discrete fractures. In this study, we use the numerical simulator CFRAC to analyse pressure drops commonly observed during stimulation of deep geothermal wells. We develop a conceptual model of a fractured geothermal reservoir to analyse the conditions required to produce pressure drops and their consequences on the evolution of seismicity, fluid pressure, and fracture permeability throughout the system. For this, we combine two fracture sets, one able to be stimulated by shear-mode fracturing and another one able to be stimulated by opening-mode fracturing. With this combination, the pressure drop can be triggered by a seismic event in the shear-stimulated fracture that is hydraulically connected with an opening-mode fracture. Our results indicate that pressure drops are not produced by the new volume created by shear dilatancy, but by the opening of the conjugated tensile fractures. Finally, our results reveal that natural fracture/splay fracture interaction can potentially explain the observed pressure drops at the Rittershoffen geothermal site.http://link.springer.com/article/10.1186/s40517-018-0110-7Enhanced geothermal reservoirsPressure dropsReservoir simulationInduced seismicityFracture networks |
| spellingShingle | Guillem Piris Albert Griera Enrique Gomez-Rivas Ignasi Herms Mark W. McClure Jack H. Norbeck Fluid pressure drops during stimulation of segmented faults in deep geothermal reservoirs Geothermal Energy Enhanced geothermal reservoirs Pressure drops Reservoir simulation Induced seismicity Fracture networks |
| title | Fluid pressure drops during stimulation of segmented faults in deep geothermal reservoirs |
| title_full | Fluid pressure drops during stimulation of segmented faults in deep geothermal reservoirs |
| title_fullStr | Fluid pressure drops during stimulation of segmented faults in deep geothermal reservoirs |
| title_full_unstemmed | Fluid pressure drops during stimulation of segmented faults in deep geothermal reservoirs |
| title_short | Fluid pressure drops during stimulation of segmented faults in deep geothermal reservoirs |
| title_sort | fluid pressure drops during stimulation of segmented faults in deep geothermal reservoirs |
| topic | Enhanced geothermal reservoirs Pressure drops Reservoir simulation Induced seismicity Fracture networks |
| url | http://link.springer.com/article/10.1186/s40517-018-0110-7 |
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