scholarly journals Impact of injection rate ramp-up on nucleation and arrest of dynamic fault slip

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
F. Ciardo ◽  
A. P. Rinaldi
Keyword(s):  
Time Scale ◽  
Injection Rate ◽  
Scaling Analysis ◽  
Dynamic Rupture ◽  
Nucleation Time ◽  
Constant Rate ◽  
Pressurization Rate ◽  
Geological Discontinuities ◽  
The Impact ◽  
Dynamic Slip

AbstractFluid injection into underground formations reactivates preexisting geological discontinuities such as faults or fractures. In this work, we investigate the impact of injection rate ramp-up present in many standard injection protocols on the nucleation and potential arrest of dynamic slip along a planar pressurized fault. We assume a linear increasing function of injection rate with time, up to a given time $$t_c$$ t c after which a maximum value $$Q_m$$ Q m is achieved. Under the assumption of negligible shear-induced dilatancy and impermeable host medium, we solve numerically the coupled hydro-mechanical model and explore the different slip regimes identified via scaling analysis. We show that in the limit when fluid diffusion time scale $$t_w$$ t w is much larger than the ramp-up time scale $$t_c$$ t c , slip on an ultimately stable fault is essentially driven by pressurization at constant rate. Vice versa, in the limit when $$t_c/t_w \gg 1$$ t c / t w ≫ 1 , the pressurization rate, quantified by the dimensionless ratio $$\dfrac{Q_m t_w}{t_c Q^*}$$ Q m t w t c Q ∗ with $$Q^*$$ Q ∗ being a characteristic injection rate scale, does impact both nucleation time and arrest distance of dynamic slip. Indeed, for a given initial fault loading condition and frictional weakening property, lower pressurization rates delay the nucleation of a finite-sized dynamic event and increase the corresponding run-out distance approximately proportional to $$\propto \left( \dfrac{Q_m t_w}{t_c Q^*}\right) ^{-0.472}$$ ∝ Q m t w t c Q ∗ - 0.472 . On critically stressed faults, instead, the ramp-up of injection rate activates quasi-static slip which quickly turn into a run-away dynamic rupture. Its nucleation time decreases non-linearly with increasing value of $$\dfrac{Q_m t_w}{t_c Q^*}$$ Q m t w t c Q ∗ and it may precede (or not) the one associated with fault pressurization at constant rate only.

scholarly journals Impact of injection rate ramp-up on nucleation and arrest of dynamic fault slip

2021 ◽  
Author(s):  
Federico Ciardo ◽  
Antonio Pio Rinaldi
Keyword(s):  
Time Scale ◽  
Injection Rate ◽  
Scaling Analysis ◽  
Dynamic Rupture ◽  
Nucleation Time ◽  
Constant Rate ◽  
Pressurization Rate ◽  
Geological Discontinuities ◽  
The Impact ◽  
Dynamic Slip

Fluid injection into underground formations reactivates preexisting geological discontinuities such as faults or fractures. In this work, we investigate the impact of injection rate ramp-up present in many standard injection protocols on the nucleation and potential arrest of dynamic slip along a planar pressurized fault. We assume a linear increasing function of injection rate with time, up to a given time tc after which a maximum value Qm is achieved. Under the assumption of negligible shear-induced dilatancy and impermeable host medium, we solve numerically the coupled hydro-mechanical model and explore the different slip regimes identified via scaling analysis. We show that in the limit when fluid diffusion time scale tw is much larger than the ramp-up time scale tc, slip on an ultimately stable fault is essentially driven by pressurization at constant rate. Vice versa, in the limit when tc/tw ≫ 1, the pressurization rate, quantified by the dimensionless ratio (Qm tw / tc Q∗), does impact both nucleation time and arrest distance of dynamic slip. Indeed, for a given initial fault loading condition and frictional weakening property, lower pressurization rates delay the nucleation of a finite-sized dynamic event and increase the corresponding run-out distance approximately proportional to (Qm tw / tc Q∗)^(-0.472). On critically stressed faults, instead, the ramp-up of injection rate activates quasi-static slip which quickly turn into a run-away dynamic rupture. Its nucleation time decreases non-linearly with increasing value of (Qm tw / tc Q∗) and it may precede (or not) the one associated with fault pressurization at constant rate only.

Simulation of Anthrax Spore Transport and Inactivation in a Room: Scaling Analysis

2005 ◽  
Author(s):  
Sankalp Soni ◽  
Bakhtier Farouk ◽  
Charles N. Haas
Keyword(s):  
Ventilation Rate ◽  
Injection Rate ◽  
Circulation System ◽  
Scaling Analysis ◽  
Anthrax Spore ◽  
Disinfection Process ◽  
Spore Release ◽  
Anthrax Spores ◽  
Quantitative Understanding ◽  
The Impact

Decontamination of large indoor spaces and buildings following release of biological agents is challenging, as the response to the fall 2001 anthrax-release events indicate. The ability to efficiently and rapidly decontaminate rooms/buildings is limited by the lack of quantitative understanding of the behavior of agent transport, and decontaminants. In response to any new releases it would be necessary to rapidly determine the optimal way to decontaminate the enclosed spaces. In the present study, we numerically simulate a biological agent (anthrax spores) transport and its inactivation by a decontaminant (chlorine dioxide). Such simulations can help us in deciding on decontamination strategies and also in better designs of the buildings and the associated air circulation system to minimize the risks in case of potential agent release. Furthermore, the study also determines the impact of scaling on predicted behavior of the agent distribution and disinfection process. From numerical simulations, a relationship for the inactivation time is obtained as a function of room geometry, ventilation rate, initial number of anthrax spore release, disinfectant injection rate and reaction kinetics. Such a relationship would help in determining decontamination strategies and in optimization of the decontamination processes.

scholarly journals An Enhanced Intrinsic Time-Scale Decomposition Method Based on Adaptive Lévy Noise and Its Application in Bearing Fault Diagnosis

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 617
Author(s):  
Jianpeng Ma ◽  
Shi Zhuo ◽  
Chengwei Li ◽  
Liwei Zhan ◽  
Guangzhu Zhang
Keyword(s):  
Fault Diagnosis ◽  
Time Scale ◽  
Lévy Noise ◽  
Model Parameters ◽  
Rolling Bearings ◽  
Intrinsic Time ◽  
Time Scale Decomposition ◽  
Weak Fault ◽  
Levy Noise ◽  
The Impact

When early failures in rolling bearings occur, we need to be able to extract weak fault characteristic frequencies under the influence of strong noise and then perform fault diagnosis. Therefore, a new method is proposed: complete ensemble intrinsic time-scale decomposition with adaptive Lévy noise (CEITDALN). This method solves the problem of the traditional complete ensemble intrinsic time-scale decomposition with adaptive noise (CEITDAN) method not being able to filter nonwhite noise in measured vibration signal noise. Therefore, in the method proposed in this paper, a noise model in the form of parameter-adjusted noise is used to replace traditional white noise. We used an optimization algorithm to adaptively adjust the model parameters, reducing the impact of nonwhite noise on the feature frequency extraction. The experimental results for the simulation and vibration signals of rolling bearings showed that the CEITDALN method could extract weak fault features more effectively than traditional methods.

scholarly journals GNSS-to-GNSS time offsets: study on the broadcast of a common reference time

GPS Solutions ◽  
2021 ◽  
Vol 25 (2) ◽  
Author(s):  
Ilaria Sesia ◽  
Giovanna Signorile ◽  
Tung Thanh Thai ◽  
Pascale Defraigne ◽  
Patrizia Tavella
Keyword(s):  
Time Scales ◽  
Time Scale ◽  
Reference Time ◽  
Single Time ◽  
Common Reference ◽  
Prediction Quality ◽  
Common Time ◽  
Time Offset ◽  
The Impact ◽  
Low Uncertainty

AbstractWe present two different approaches to broadcasting information to retrieve the GNSS-to-GNSS time offsets needed by users of multi-GNSS signals. Both approaches rely on the broadcast of a single time offset of each GNSS time versus one common time scale instead of broadcasting the time offsets between each of the constellation pairs. The first common time scale is the average of the GNSS time scales, and the second time scale is the prediction of UTC already broadcast by the different systems. We show that the average GNSS time scale allows the estimation of the GNSS-to-GNSS time offset at the user level with the very low uncertainty of a few nanoseconds when the receivers at both the provider and user levels are fully calibrated. The use of broadcast UTC prediction as a common time scale has a slightly larger uncertainty, which depends on the broadcast UTC prediction quality, which could be improved in the future. This study focuses on the evaluation of two different common time scales, not considering the impact of receiver calibration, at the user and provider levels, which can nevertheless have an important impact on GNSS-to-GNSS time offset estimation.

scholarly journals The Impact of the North Atlantic Oscillation on Climate through Its Influence on the Atlantic Meridional Overturning Circulation

2016 ◽  
Vol 29 (3) ◽  
pp. 941-962 ◽  
Author(s):  
Thomas L. Delworth ◽  
Fanrong Zeng
Keyword(s):  
North Atlantic ◽  
Time Scale ◽  
Atlantic Meridional Overturning Circulation ◽  
Meridional Overturning Circulation ◽  
The North ◽  
Hemispheric Temperature ◽  
Meridional Overturning ◽  
The North Atlantic Oscillation ◽  
The Impact ◽  
Model Ocean

Abstract The impact of the North Atlantic Oscillation (NAO) on the Atlantic meridional overturning circulation (AMOC) and large-scale climate is assessed using simulations with three different climate models. Perturbation experiments are conducted in which a pattern of anomalous heat flux corresponding to the NAO is added to the model ocean. Differences between the perturbation experiments and a control illustrate how the model ocean and climate system respond to the NAO. A positive phase of the NAO strengthens the AMOC by extracting heat from the subpolar gyre, thereby increasing deep-water formation, horizontal density gradients, and the AMOC. The flux forcings have the spatial structure of the observed NAO, but the amplitude of the forcing varies in time with distinct periods varying from 2 to 100 yr. The response of the AMOC to NAO variations is small at short time scales but increases up to the dominant time scale of internal AMOC variability (20–30 yr for the models used). The amplitude of the AMOC response, as well as associated oceanic heat transport, is approximately constant as the time scale of the forcing is increased further. In contrast, the response of other properties, such as hemispheric temperature or Arctic sea ice, continues to increase as the time scale of the forcing becomes progressively longer. The larger response is associated with the time integral of the anomalous oceanic heat transport at longer time scales, combined with an increased impact of radiative feedback processes. It is shown that NAO fluctuations, similar in amplitude to those observed over the last century, can modulate hemispheric temperature by several tenths of a degree.

The New Flow Control Devices Autonomously Controlling the Performance of Matrix Acid Stimulation Operations in Carbonate Reservoirs

2021 ◽  
Author(s):  
Mojtaba Moradi ◽  
Michael R Konopczynski
Keyword(s):  
Flow Control ◽  
Dynamic Change ◽  
Injection Rate ◽  
Control Flow ◽  
Carbonate Reservoir ◽  
Operating Conditions ◽  
Carbonate Reservoirs ◽  
High Permeability ◽  
The Impact ◽  
Stimulation Of

Abstract Matrix acidizing is a common but complex stimulation treatment that could significantly improve production/injection rate, particularly in carbonate reservoirs. However, the desired improvement in all zones of the well by such operation may not be achieved due to existing and/or developing reservoir heterogeneity. This paper describes how a new flow control device (FCD) previously used to control water injection in long horizontal wells can also be used to improve the conformance of acid stimulation in carbonate reservoirs. Acid stimulation of a carbonate reservoir is a positive feedback process. Acid preferentially takes the least resistant path, an area with higher permeability or low skin. Once acid reacts with the formation, the injectivity in that zone increases, resulting in further preferential injection in the stimulated zone. Over-treating a high permeability zone results in poor distribution of acid to low permeability zones. Mechanical, chemical or foam diversions have been used to improve stimulation conformance along the wellbore, however, they may fail in carbonate reservoirs with natural fractures where fracture injectivity dominates the stimulation process. A new FCD has been developed to autonomously control flow and provide mechanical diversion during matrix stimulation. Once a predefined upper limit flowrate is reached at a zone, the valve autonomously closes. This eliminates the impact of thief zone on acid injection conformance and maintains a prescribed acid distribution. Like other FCDs, this device is installed in several compartments in the wells. The device has two operating conditions, one, as a passive outflow control valve, and two, as a barrier when the flow rate through the valve exceeds a designed limit, analogous to an electrical circuit breaker. Once a zone has been sufficiently stimulated by the acid and the injection rate in that zone exceeds the device trip point, the device in that zone closes and restricts further stimulation. Acid can then flow to and stimulate other zones This process can be repeated later in well life to re-stimulate zones. This performance enables the operators to minimise the impacts of high permeability zones on the acid conformance and to autonomously react to a dynamic change in reservoirs properties, specifically the growth of wormholes. The device can be installed as part of lower completions in both injection and production wells. It can be retrofitted in existing completions or be used in a retrievable completion. This technology allows repeat stimulation of carbonate reservoirs, providing mechanical diversion without the need for coiled tubing or other complex intervention. This paper will briefly present an overview of the device performance, flow loop testing and some results from numerical modelling. The paper also discusses the completion design workflow in carbonates reservoirs.

scholarly journals Has erosion globally increased? Long-term erosion rates as a function of climate derived from the impact crater inventory

2018 ◽  
Author(s):  
Stefan Hergarten ◽  
Thomas Kenkmann
Keyword(s):  
Time Scale ◽  
Impact Crater ◽  
Regional Effect ◽  
Tropical Zone ◽  
Erosion Rates ◽  
Continental Scale ◽  
River Loads ◽  
The Impact

Abstract. Worldwide erosion rates seem to have increased strongly since the beginning of the Quaternary, but there is still discussion about the role of glaciation as a potential driver and even whether the increase is real at all or an artefact due to losses in the long-term sedimentary record. In this study we derive estimates of average erosion rates on the time scale of some tens of million years from the terrestrial impact crater inventory. This approach is completely independent from all other methods to infer erosion rates such as river loads, preserved sediments, cosmogenic nuclides and thermochronometry. Our approach yields average erosion rates as a function of present-day topography and climate. The results confirm that topography accounts for the main part of the huge variation of erosion on Earth, but also identifies a significant systematic dependence on climate in contrast to several previous studies. We found a fivefold increase in erosional efficacy from the cold regimes to the tropical zone and that temperate and arid climates are very similar in this context. Combining our results to a worldwide mean erosion rate we found that erosion rates on the time scale of some tens of million years are at least as high as present-day rates and suggest that glaciation has a rather regional effect with a limited impact at the continental scale.

scholarly journals When to Spray: a Time-Scale Calculus Approach to Controlling the Impact of West Nile Virus

2009 ◽  
Vol 14 (2) ◽  
Author(s):  
Diana Thomas ◽  
Marion Weedermann ◽  
Lora Billings ◽  
Joan Hoffacker ◽  
Robert A. Washington-Allen
Keyword(s):  
West Nile Virus ◽  
Time Scale ◽  
West Nile ◽  
Time Scale Calculus ◽  
The Impact

scholarly journals Fermions on wobbling kinks: normal versus quasinormal modes

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
João G. F. Campos ◽  
Azadeh Mohammadi
Keyword(s):  
Transition Probabilities ◽  
Transition Probability ◽  
Quasinormal Modes ◽  
Golden Rule ◽  
Coupling Constants ◽  
Large Coupling ◽  
Constant Rate ◽  
Fermi's Golden Rule ◽  
The Impact ◽  
Fermi’S Golden Rule

Abstract The system consisting of a fermion in the background of a wobbling kink is studied in this paper. To investigate the impact of the wobbling on the fermion-kink interaction, we employ the time-dependent perturbation theory formalism in quantum mechanics. To do so, we compute the transition probabilities between states given in terms of the Bogoliubov coefficients. We derive Fermi’s golden rule for the model, which allows the transition to the continuum at a constant rate if the fermion-kink coupling constant is smaller than the wobbling frequency. Moreover, we study the system replacing the shape mode with a quasinormal mode. In this case, the transition rate to continuum decays in time due to the leakage of the mode, and the final transition probability decreases sharply for large coupling constants in a way that is analogous to Fermi’s golden rule. Throughout the paper, we compare the perturbative results with numerical simulations and show that they are in good agreement.

scholarly journals The life cycle impacton the distribution of construction and technical expertise tasks

2020 ◽  
Vol 17 (5) ◽  
pp. 130-140
Author(s):  
N. V. Lazareva ◽  
◽  
A. Yu. Zinoviev ◽  
Keyword(s):  
Conflict Resolution ◽  
Life Cycle ◽  
Time Scale ◽  
Theoretical Basis ◽  
Technological Progress ◽  
Construction Projects ◽  
Technical Expertise ◽  
Institutional Affiliation ◽  
Capital Construction ◽  
The Impact

Acceleration of scientific and technological progress, increasing requirements for safety, comfort, and efficiency of capital construction projects, and the impact of the external economic environment, among other things, determine organizational transformations not only in investment and construction activities, but also in all periods and stages of the life cycle of buildings and structures. At the same time, increasing complexity of the organizational foundations of construction and housing and communal complexes, growing number and intensity of interactions between contractors lead to the emergence of disputes and conflicts between them and as a result, to the need to get out of such situations. A tool for fair conflict resolution can be a construction and technical expertise, which can be classified as judicial, pre-trial and corporate, depending on the institutional affiliation. This article discusses the distribution of tasks of construction and technical expertise on the time scale of the object's life cycle, as well as the theoretical basis for the manifestation of these phenomena.

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