A new method to estimate location and slip of simulated rock failure events

Heinze, Thomas; Galvan, Boris; Miller, Stephen A.

doi:10.1016/j.tecto.2015.03.009

Cited by 14 publications

(8 citation statements)

References 59 publications

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“…Future models might also include fracture roughness and morphology and solving the full equilibrium equations to estimate aperture changes that influence permeability. Finally, including a method to estimate magnitude from computed slip [37], not currently modeled, is essential for a mechanistic assessment of seismic hazard associated with injection. Induced seismicity cannot be quantified in terms of magnitude as fracture slip in the fractures is not computed.…”

Section: Resultsmentioning

confidence: 99%

On the Role of Thermal Stresses during Hydraulic Stimulation of Geothermal Reservoirs

Jansen

Miller

2017

Geofluids

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Massive quantities of fluid are injected into the subsurface during the creation of an engineered geothermal system (EGS) to induce shear fracture for enhanced reservoir permeability. In this numerical thermoelasticity study, we analyze the effect of cold fluid injection on the reservoir and the resulting thermal stress change on potential shear failure in the reservoir. We developed an efficient methodology for the coupled simulation of fluid flow, heat transport, and thermoelastic stress changes in a fractured reservoir. We performed a series of numerical experiments to investigate the effects of fracture and matrix permeability and fracture orientation on thermal stress changes and failure potential. Finally, we analyzed thermal stress propagation in a hypothetical reservoir for the spatial and temporal evolution of possible thermohydraulic induced shear failure. We observe a strong influence of the hydraulic reservoir properties on thermal stress propagation. Further, we find that thermal stress change can lead to induced shear failure on nonoptimally oriented fractures. Our results suggest that thermal stress changes should be taken into account in all models for long-term fluid injections in fractured reservoirs.

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Section: Resultsmentioning

confidence: 99%

On the Role of Thermal Stresses during Hydraulic Stimulation of Geothermal Reservoirs

Jansen

Miller

2017

Geofluids

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“…On a field scale, many similarities have been observed between seismicity and AE signal such as, the path of crack propagation and energy release. However, the frequency of seismic wave is different from that of the AE signal [39]. Seismic wave amplitude can be calculated with the moment tensor method.…”

Section: Moment Tensor Methodsmentioning

confidence: 99%

Effect of Injection Site on Fault Activation and Seismicity during Hydraulic Fracturing

Chong

Chen

2017

Energies

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Hydraulic fracturing is a key technology to stimulate oil and gas wells to increase production in shale reservoirs with low permeability. Generally, the stimulated reservoir volume is performed based on pre-existing natural fractures (NF). Hydraulic fracturing in shale reservoirs with large natural fractures (i.e., faults) often results in fault activation and seismicity. In this paper, a coupled hydro-mechanical model was employed to investigate the effects of injection site on fault activation and seismicity. A moment tensor method was used to evaluate the magnitude and affected areas of seismic events. The micro-parameters of the proposed model were calibrated through analytical solutions of the interaction between hydraulic fractures (HF) and the fault. The results indicated that the slip displacement and activation range of the fault first decreased, then remained stable with the increase in the distance between the injection hole and the fault (L if). In the scenario of the shortest L if (L if = 10 m), the b-value-which represents the proportion of frequency of small events in comparison with large events-reached its maximum value, and the magnitude of concentrated seismic events were in the range of −3.5 to −1.5. The frequency of seismic events containing only one crack was the lowest, and that of seismic events containing more than ten cracks was the highest. The interaction between the injection-induced stress disturbance and fault slip was gentle when L if was longer than the critical distance (L if = 40-50 m). The results may help optimize the fracturing treatment designs during hydraulic fracturing.

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“…Based on the FEM/DEM method, Lisjak et al [17] proposed a new model to simulate microseismic events, which described the fracture process in rock materials using three parameters: -value, AE rate, and -value. Heinze et al [18] developed a poroelastoplastic continuum model, which divided and quantified rock failure into a prefailure stage, a massive failure stage, and a macroscopic failure stage. Through sensitivity analysis, Tang et al [19,20] evaluated the strength and fracture processes of rock materials and applied the Weibull distribution rule of AE events to detect rock fractures and deformations.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Acoustic Emission Events of Argillaceous Sandstones under Confining Pressure

Chong

et al. 2017

Mathematical Problems in Engineering

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At the laboratory scale, locating acoustic emission (AE) events is a comparatively mature method for evaluating cracks in rock materials, and the method plays an important role in numerical simulations. This study is aimed at developing a quantitative method for the measurement of acoustic emission (AE) events in numerical simulations. Furthermore, this method was applied to estimate the crack initiation, propagation, and coalescence in rock materials. The discrete element method-acoustic emission model (DEM-AE model) was developed using an independent subprogram. This model was designed to calculate the scalar seismic tensor of particles in the process of movement and further to determine the magnitude of AE events. An algorithm for identifying the same spatiotemporal AE event is being presented. To validate the model, a systematic physical experiment and numerical simulation for argillaceous sandstones were performed to present a quantitative comparison of the results with confining pressure. The results showed good agreement in terms of magnitude and spatiotemporal evolution between the simulation and the physical experiment. Finally, the magnitude of AE events was analyzed, and the relationship between AE events and microcracks was discussed. This model can provide the research basis for preventing seismic hazards caused by underground coal mining.

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A new method to estimate location and slip of simulated rock failure events

Cited by 14 publications

References 59 publications

On the Role of Thermal Stresses during Hydraulic Stimulation of Geothermal Reservoirs

On the Role of Thermal Stresses during Hydraulic Stimulation of Geothermal Reservoirs

Effect of Injection Site on Fault Activation and Seismicity during Hydraulic Fracturing

Numerical Investigation of Acoustic Emission Events of Argillaceous Sandstones under Confining Pressure

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