Meter-scale stress heterogeneities and stress redistribution drive complex fracture slip and fracture growth during a hydraulic stimulation experiment
| Autor: | Hannes Krietsch, Stefan Wiemer, Linus Villiger, Grzegorz Kwiatek, Domenico Giardini, Joseph Doetsch, Valentin Gischig, Florian Amann, Mohammadreza Jalali |
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| Rok vydání: | 2021 |
| Předmět: |
010504 meteorology & atmospheric sciences
Scale (ratio) Complex fracture Slip (materials science) Induced seismicity 010502 geochemistry & geophysics 01 natural sciences Stress (mechanics) Stress redistribution Geophysics Geochemistry and Petrology Fracture (geology) Metre Geotechnical engineering Geology Earthquake source observations Creep and deformation Fracture and flow Permeability and porosity 0105 earth and related environmental sciences |
| Zdroj: | Geophysical Journal International Geophysical Journal International, 225 (3) |
| Popis: | SUMMARY We investigated the induced seismicity, source mechanisms and mechanical responses of a decametre-scale hydraulic stimulation of a pre-existing shear zone in crystalline rock, at the Grimsel Test Site, Switzerland. The analysis reveals the metre-scale complexity of hydraulic stimulation, which remains hidden at the reservoir-scale. High earthquake location accuracy allowed the separation of four distinct clusters, of which three were attributed to the stimulation of fractures in the damage zone of the shear zone. The source mechanism of the larger-magnitude seismicity varied by cluster, and suggests a heterogeneous stress field already prevailing before stimulation, which is further modified during stimulation. In the course of the experiment, stress redistribution led to the aseismic initiation of a tensile-dominated fracture, which induced seismicity in the fourth of the identified seismic clusters. The streaky pattern of seismicity separated by zones without seismicity suggests fluid flow in conduits along existing fracture planes. The observed submetre scale complexity questions the forecasting ability of induced seismic hazard at the reservoir scale from small-scale experiments. |
| Databáze: | OpenAIRE |
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