Meier, Tobias (2020) D5.5 Validation of model for fluid migration against field site data. Documentation. Science For Clean Energy Project.
Full text not available from this repository.Abstract
The S4CE considers a variety of sub-surface geo-energy operations. Among others, the extraction of resources and energy from the subsurface is commonly linked with hazards like collapse of mines or shafts, possible pollution of the subsurface and/or induced seismicity. The latter has aroused attention in the previous years due to newly developed techniques for hydraulically stimulation of rock masses for the extraction of hydrocarbons from lowpermeable shale rocks (e.g., unconventional reservoirs) or enhancing geothermal reservoirs by massive hydraulic stimulations to create fluid pathways between geothermal wells. However, not only hydraulic stimulations can cause induced seismicity. Injection of wastewater has also been linked to seismicity in the previous years as for example shown by Langenbruch et al. (2018). In order to understand the influence of fluid injections on induced seismicity, the deliverable D5.5 “Validation of model for fluid migration against field site data” has been planned within the S4CE consortium. The deliverable forms a key aspect within S4CE, since the extraction of geothermal energy is part of renewable energy production, which is needed for a smooth transition from hydrocarbon-based energy production towards a C02-free energy production. It is therefore of importance to reduce the risks related to geothermal operations and to enable a safe production of this renewable energy. The S4CE consortium has access to a few sites across Europe. Among these, the St. Gallen geothermal site has been selected because the related recorded seismicity had already been processed by the Swiss Seismological Service (SED). The SED located the seismicity in St. Gallen to a depth below the injection well, situated in a most-likely over-pressurized trough of Permo-Carboniferous age. The distance from the seismicity to the injection well makes the fluid transport mechanism from the well to the Permo-Carboniferous Trough (PCT) challenging to understand, since an over-pressurized trough would cause fluids to migrate upwards rather than downwards. Structural data as well as injection data have been made available to the S4CE consortium, which, therefore, makes the St. Gallen data set an excellent data set for numerical simulations, which might be a tool for predictions of induced seismicity (e.g., Meier and Backers, 2017; Gaucher et al., 2015 and references therein). The findings presented in D5.5 shall provide a better understanding on how injected fluids in fault-based subsurface reservoirs can induce seismicity and thereby damage above-surface constructions. For this purpose, a structural subsurface model has been reevaluated and enhanced to accommodate an over-pressurized PCT beneath the geothermal well the stress field has been determined injection data has been collected and implemented into the numerical models two scenarios have been investigated numerically that could have caused the observed seismicity: o poroelastic stress transfer from the well to the PCT o fast transport of the fluid from the well to the PCT via existing fracture systems
| Item Type: | Reports (Documentation) |
|---|---|
| Subjects: | Methodology > Method and procesing > Technology-seismicity interaction Region > Switzerland > St. Gallen Inducing technology > Geothermal energy production |
| Project: | S4CE > ST GALLEN: geothermal project |