scholarly journals On the Relationship Between Fault Permeability Increases, Induced Stress Perturbation, and the Growth of Aseismic Slip During Fluid Injection

2018 ◽  
Vol 45 (20) ◽  
Author(s):  
Frédéric Cappa ◽  
Yves Guglielmi ◽  
Christophe Nussbaum ◽  
Jens Birkholzer
Keyword(s):  
Fluid Injection ◽  
Aseismic Slip ◽  
Induced Stress ◽  
Fault Permeability ◽  
The Relationship

Fluid-induced aseismic fault slip outpaces pore-fluid migration

Science ◽  
2019 ◽  
Vol 364 (6439) ◽  
pp. 464-468 ◽  
Author(s):  
Pathikrit Bhattacharya ◽  
Robert C. Viesca
Keyword(s):  
Pore Fluid ◽  
Fluid Injection ◽  
Fluid Migration ◽  
Aseismic Slip ◽  
Earthquake Triggering ◽  
Effective Normal Stress ◽  
Shear Rupture ◽  
Stress Changes ◽  
Slip History ◽  
Rupture Model

Earthquake swarms attributed to subsurface fluid injection are usually assumed to occur on faults destabilized by increased pore-fluid pressures. However, fluid injection could also activate aseismic slip, which might outpace pore-fluid migration and transmit earthquake-triggering stress changes beyond the fluid-pressurized region. We tested this theoretical prediction against data derived from fluid-injection experiments that activated and measured slow, aseismic slip on preexisting, shallow faults. We found that the pore pressure and slip history imply a fault whose strength is the product of a slip-weakening friction coefficient and the local effective normal stress. Using a coupled shear-rupture model, we derived constraints on the hydromechanical parameters of the actively deforming fault. The inferred aseismic rupture front propagates faster and to larger distances than the diffusion of pressurized pore fluid.

Stress Perturbation From Aseismic Slip Drives the Seismic Front During Fluid Injection in a Permeable Fault

2020 ◽  
Vol 125 (7) ◽  
Author(s):  
Nicolas Wynants‐Morel ◽  
Frédéric Cappa ◽  
Louis De Barros ◽  
Jean‐Paul Ampuero
Keyword(s):  
Fluid Injection ◽  
Aseismic Slip

Induced seismicity associated with fluid injection into a fractured rock mass

2020 ◽  
Author(s):  
Brice Lecampion ◽  
Federico Ciardo ◽  
Alexis Saèz Uribe ◽  
Andreas Möri
Keyword(s):  
Rock Mass ◽  
Percolation Threshold ◽  
Pore Pressure ◽  
Finite Volume ◽  
Fractured Rock ◽  
Fluid Injection ◽  
Aseismic Slip ◽  
Dynamic Rupture ◽  
Fractured Rock Mass

<p>We investigate via numerical modeling the growth of an aseismic rupture and the possible nucleation of a dynamic rupture driven by fluid injection into a fractured rock mass. We restrict to the case of highly transmissive fractures compared to the rock matrix at the scale of the injection duration and thus assume an impermeable matrix. We present a new 2D hydro-mechanical solver allowing to treat a large number of pre-existing frictional discontinuities. The quasi-static (or quasi-dynamic) balance of momentum is discretized using boundary elements while fluid flow inside the fracture is discretized via finite volume. A fully implicit scheme is used for time integration. Combining a hierarchical matrix approximation of the original boundary element matrix with a specifically developed block pre-conditioner enable a robust and efficient solution of large problems (with up to 10<sup>6</sup> unknowns). In order to treat accurately fractures intersections, we use piece-wise linear displacement discontinuities element for elasticity and a vertex centered finite volume method for flow.</p><p>We first consider the case of a randomly oriented discrete fracture network (DFN) having friction neutral properties. We discuss the very different behavior associated with marginally pressurized versus critically stressed conditions. As an extension of the case of a planar fault (Bhattacharya and Viesca, Science, 2019), the injection into a DFN problem is governed by the distribution (directly associated with fracture orientation) of a dimensionless parameter combining the local stress criticality (function of the in-situ principal effective stress, friction coefficient and local fracture orientation) and the normalized injection over-pressure. The percolation threshold of the DFN which characterizes the hydraulic connectivity of the network plays an additional role in fluid driven shear cracks growth. Our numerical simulations show that a critically stressed DFN exhibits fast aseismic slip growth (much faster than the fluid pore-pressure disturbance front propagation) regardless of the DFN percolation threshold. This is because the slipping patch growth is driven by the cascades of shear activation due to stress interactions as fractures get activated. On the other hand, the scenario is different for marginally pressurized / weakly critically stressed DFN. The aseismic slip propagation is then tracking pore pressure diffusion inside the DFN. As a result, the DFN percolation threshold plays an important role with low percolation leading to fluid localization and thus restricted aseismic rupture growth.</p><p>We then discuss the case of fluid injection into a fault damage zone. Using a linear frictional weakening model for the fault, we investigate the scenario of the nucleation of a dynamic rupture occurring after the end of the injection (as observed in several instances in the field). We delimit the injection and in-situ conditions supporting such a possibility.</p>

scholarly journals The Relationship Between Seismic and Aseismic Slip on the Philippine Fault on Leyte Island: Bayesian Modeling of Fault Slip and Geothermal Subsidence

2020 ◽  
Vol 125 (12) ◽  
Author(s):  
John Dale B. Dianala ◽  
Romain Jolivet ◽  
Marion Y. Thomas ◽  
Yo Fukushima ◽  
Barry Parsons ◽  
...  
Keyword(s):  
Bayesian Modeling ◽  
Fault Slip ◽  
Aseismic Slip ◽  
The Relationship

scholarly journals The Relationship between Mining-Induced Stress and Coal Gas under an Optimized Support Scheme: A Case Study in the Guanyinshan Coal Mine, China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Tianjun Zhang ◽  
Jiaokun Wu ◽  
Yong Chen ◽  
Hong Ding ◽  
Hongyu Ma ◽  
...  
Keyword(s):  
Gas Pressure ◽  
Gas Content ◽  
Rock Support ◽  
Drill Cuttings ◽  
Coal Gas ◽  
Gas Desorption ◽  
Induced Stress ◽  
Coal And Gas Outbursts ◽  
Residual Gas ◽  
The Relationship

Stress is one of the main factors influencing coal and gas outbursts. The apparent effects of the crustal stress, the structural stress, and the mining-induced stress increase as the depth of mining increases. At present, there have been few studies of the relationship between the comprehensive analyses of the crustal stress, mining-induced stress, and coal gas. The in situ measurement of the relationship between stress-related behaviors and coal gas under the influence of mining was conducted through experimental analysis of surrounding rock support and coal and gas outburst control and optimization of surrounding rock support materials and system construction. The results showed that the mining-induced stress first increased to a peak value, then gradually decreased, and tended to stabilize as the footage progresses. Stress appears at 96 m ahead due to mining; after 57 m of advancing, there is a large increase until it passes through this area. The stress in front of the working face increases linearly, and the increase range is obviously larger than that of the coal body in a certain range on both sides. The support anchoring force gradually decreased and tended to be stable after rapidly increasing to a maximum value. The deep displacement of the roof increased linearly and tended to be stable after reaching an accumulated displacement which can reach 16-28 mm. The residual gas pressure in front of mining operations decreased rapidly, and beyond 15 m on each side of the roadway, it decreased significantly. The residual gas pressure and gas content were consistent with the gas desorption index of drill cuttings due to the influences of gas predrainage and mining. The stress along the direction of the roadway and the residual gas content, the residual gas pressure, and the gas desorption index of drill cuttings conform to the logarithmic functional relationship. The research results provide a basis for the comprehensive prevention and control of coal and gas outbursts from multiple angles considering stress, coal, and gas.

ON THE MICROMECHANICS MODELING OF MICROCRACK TOUGHENING IN CERAMIC MATERIALS

1995 ◽  
Vol 19 (3) ◽  
pp. 317-329 ◽  
Author(s):  
S.X. Gong
Keyword(s):  
Main Crack ◽  
Current Model ◽  
Ceramic Materials ◽  
Leading Order ◽  
Induced Stress ◽  
General Series ◽  
Fundamental Understanding ◽  
Microcrack Toughening ◽  
Micromechanics Modeling ◽  
The Relationship

The development of advanced ceramic materials with enhanced toughness relies upon the fundamental understanding and accurate modeling of various toughening mechanisms in these materials. In this paper, a rigorous micromechanics approach is proposed to treat the microcrack toughening phenomena in ceramics. The microcracking zone is modeled as a region containing multiple discrete microcracks near the tip of a dominant crack and the main crack-microcrack interactions are studied in detail. The analysis is based upon the use of the complex potentials of Muskhelishvili and an appropriate superposition scheme. The induced stress intensity factor at the main crack is obtained in a general series form and the leading order explicit solution is utilized to investigate the associated shielding and amplification effects and to provide a quantitative analysis of the microcrack toughening. Both a stationary and a steadily growing main crack are considered and the effect of the release of residual stresses has been taken into account. The relationship between the current model and other existing ones is also discussed.

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