scholarly journals Non-linear effects of pore pressure increase on seismic event generation in multi-degree-of-freedom rate-and-state model of tectonic fault sliding

2016 ◽  
Author(s):  
Sergey B. Turuntaev ◽  
Vasily Y. Riga
Keyword(s):  
Pore Pressure ◽  
Friction Model ◽  
Degree Of Freedom ◽  
Pressure Increase ◽  
Fluid Injection ◽  
Model Parameters ◽  
Tectonic Fault ◽  
Rate And State Friction ◽  
Linear Effects ◽  
Event Generation

Abstract. The influence of fluid injection on tectonic fault sliding and generation of seismic events was studied by multi-degree-of-freedom rate-and-state friction model with two-parametric friction law. A system of blocks (up to 25 blocks) elastically connected with each other and connected by elastic springs to a constant-velocity moving driver was considered. Variation of the pore pressure due to fluid injection led to variation of effective stress between the first block and the substrate. Initially the block system was in steady-sliding state, then its state was changed by the pore pressure increase. The influence of the model parameters (number of the blocks, the spring stiffness, velocity weakening parameter) on the seismicity variations were considered. Various slip patterns were obtained and analysed.

scholarly journals Non-linear effects of pore pressure increase on seismic event generation in a multi-degree-of-freedom rate-and-state model of tectonic fault sliding

2017 ◽  
Vol 24 (2) ◽  
pp. 215-225 ◽  
Author(s):  
Sergey B. Turuntaev ◽  
Vasily Y. Riga
Keyword(s):  
Pore Pressure ◽  
Seismic Event ◽  
Friction Model ◽  
Degree Of Freedom ◽  
Pressure Increase ◽  
Fluid Injection ◽  
Model Parameters ◽  
Tectonic Fault ◽  
Rate And State Friction ◽  
Linear Effects

Abstract. The influence of fluid injection on tectonic fault sliding and seismic event generations was studied by a multi-degree-of-freedom rate-and-state friction model with a two-parametric friction law. A system of blocks (up to 25 blocks) elastically connected to each other and connected by elastic springs to a constant-velocity moving driver was considered. Variation of the pore pressure due to fluid injection led to variation of effective stress between the first block and the substrate. Initially the block system was in a steady-sliding state; then, its state was changed by the pore pressure increase. The influence of the model parameters (number of blocks, spring stiffness, velocity weakening parameter) on the seismicity variations was considered. Various slip patterns were obtained and analysed.

scholarly journals A framework to quantify uncertainty in critical slip distance in rate and state friction model for earthquakes

2021 ◽  
Author(s):  
Saumik Dana ◽  
Kartik Reddy Lyathakula
Keyword(s):  
Friction Model ◽  
Bayesian Inversion ◽  
Model Parameters ◽  
True Value ◽  
Rate And State Friction ◽  
Conventional Solution ◽  
Parameter Values ◽  
Quantifying Uncertainty ◽  
Earthquake Data ◽  
Slip Distance

We arrive at estimates of critical slip distance in the rate and state model for friction evolution using synthetic earthquake data via the Bayesian inference. The conventional solution to the inverse problem is the deterministic parameter values, which may not represent the true value, and quantifying uncertainty in the model parameters increases confidence in the estimation. In this work, the uncertainty in the critical slip distance is estimated by the posterior distribution obtained through the Bayesian inversion.

scholarly journals Hydro-mechanical modeling of seismogenic asperity loaded by aseismic slip through TOUGH-BIEM simulation

2020 ◽  
Author(s):  
Hideo Aochi ◽  
Jonny Rutqvist
Keyword(s):  
Pore Pressure ◽  
Injection Rate ◽  
Friction Model ◽  
Fault Slip ◽  
Boundary Integral ◽  
Fluid Volume ◽  
Fault Reactivation ◽  
Pressure Increase ◽  
Aseismic Slip ◽  
Stress Dependent

<p>We consider seismogenic asperities loaded by aseismic slip on a fault, which is induced by fluid circulation, as a simple example of fault reactivation. For this purpose, we combine two methods. The TOUGH2 (Transport Of Unsaturated Ground water and Heat) code is used for modeling the pore pressure evolution within a fault and then a Boundary Integral Equation Method (BIEM) is applied for simulating fault slip, including aseismic slip on the entire fault plane and fast slip on seismogenic asperities. The fault permeability is assumed stress-dependent and therefore is not constant but varies during a simulation. We adopt the Coulomb friction and a cyclic slip-strengthening-then-weakening friction model governing the fault slip, which allows for repeated asperity slip. We were able to demonstrate the entire process from the fluid injection, pore pressure increase, aseismic slip to seismogenic asperity slip. We tested a step-like increase of injection rate with time, which is common for hydraulic fracturing and reservoir stimulation at deep geothermal sites. Under this configuration, the pore pressure increase is not proportional to the injection rate, as the permeability depends on the stress.  Fault slip on seismogenic asperities is triggered repeatedly by surrounding aseismic slip. We find, in a given example, that the reccurence of the fast slip on asperity is approximatively proportional to the injected fluid volume, inferring that the aseismic slip amount increases proporitionally to the fluid volume as well.</p>

Analysis of seismicity caused by fluid injection

2020 ◽  
Author(s):  
Vasily Riga ◽  
Sergey Turuntaev
Keyword(s):  
Induced Seismicity ◽  
Fluid Injection ◽  
Model Parameters ◽  
Friction Law ◽  
Single Fault ◽  
Frictional Properties ◽  
Fault Behavior ◽  
Rate And State Friction ◽  
Microseismic Events ◽  
Two Parameter

<p>Induced seismicity associated with fluid injection into the subsurface is an important issue worldwide. Sometimes the fluid injection into a fault leads to aseismic creep of the fault or to microseismic events, but other times it results in more significant seismicity. In our work, we analyze the influence of various parameters of the fault and the rock, as well as the geometry of the model on induced seismicity. A case of well injecting water near a single fault was considered. To describe the slip process, several versions of the rate-and-state friction law was used. It was analyzed, how the model parameters, such as the position of the well relative to the fault, the permeability of the rock, the frictional properties of the fault affect the fault displacements. The problem of the poroelastic effect influence on the fault motion was also considered. Conditions that are favorable for the occurrence of noticeable seismicity were obtained. Difference in the fault behavior with one-parameter and two-parameter rate-and-state friction law were also considered.</p>

scholarly journals Study on Friction in Automotive Shock Absorbers Part 1: Friction Simulation Using a Dynamic Friction Model in the Contact Zone of an FEM Model

Vehicles ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 212-232
Author(s):  
Ludwig Herzog ◽  
Klaus Augsburg
Keyword(s):  
Ride Comfort ◽  
Viscous Friction ◽  
Simulation Method ◽  
Friction Model ◽  
Model Parameters ◽  
Dynamic Friction ◽  
Friction Modeling ◽  
Shock Absorbers ◽  
Operation Conditions ◽  
Wide Range

The important change in the transition from partial to high automation is that a vehicle can drive autonomously, without active human involvement. This fact increases the current requirements regarding ride comfort and dictates new challenges for automotive shock absorbers. There exist two common types of automotive shock absorber with two friction types: The intended viscous friction dissipates the chassis vibrations, while the unwanted solid body friction is generated by the rubbing of the damper’s seals and guides during actuation. The latter so-called static friction impairs ride comfort and demands appropriate friction modeling for the control of adaptive or active suspension systems. In this article, a simulation approach is introduced to model damper friction based on the most friction-relevant parameters. Since damper friction is highly dependent on geometry, which can vary widely, three-dimensional (3D) structural FEM is used to determine the deformations of the damper parts resulting from mounting and varying operation conditions. In the respective contact zones, a dynamic friction model is applied and parameterized based on the single friction point measurements. Subsequent to the parameterization of the overall friction model with geometry data, operation conditions, material properties and friction model parameters, single friction point simulations are performed, analyzed and validated against single friction point measurements. It is shown that this simulation method allows for friction prediction with high accuracy. Consequently, its application enables a wide range of parameters relevant to damper friction to be investigated with significantly increased development efficiency.

Dynamic Modeling of Channel Formation During Fluid Injection Into Unconsolidated Formations

SPE Journal ◽  
2015 ◽  
Vol 20 (04) ◽  
pp. 689-700 ◽  
Author(s):  
S.. Ameen ◽  
A. Dahi Taleghani
Keyword(s):  
Preferential Flow ◽  
Volume Fraction ◽  
Injection Pressure ◽  
Internal Erosion ◽  
Fluid Injection ◽  
Critical Threshold ◽  
Model Parameters ◽  
Flow Paths ◽  
Preferential Flow Paths ◽  
Stress Changes

Summary Injectivity loss is a common problem in unconsolidated-sand formations. Injection of water into a poorly cemented granular medium may lead to internal erosion, and consequently formation of preferential flow paths within the medium because of channelization. Channelization in the porous medium might occur when fluid-induced stresses become locally larger than a critical threshold and small grains are dislodged and carried away; hence, porosity and permeability of the medium will evolve along the induced flow paths. Vice versa, flowback during shut-in might carry particles back to the well and cause sand accumulation inside the well, and subsequently loss of injectivity. In most cases, to maintain the injection rate, operators will increase injection pressure and pumping power. The increased injection pressure results in stress changes and possibly further changes in channel patterns around the wellbore. Experimental laboratory studies have confirmed the presence of the transition from uniform Darcy flow to a fingered-pattern flow. To predict these phenomena, a model is needed to fill this gap by predicting the formation of preferential flow paths and their evolution. A model based on the multiphase-volume-fraction concept is used to decompose porosity into mobile and immobile porosities where phases may change spatially, evolve over time, and lead to development of erosional channels depending on injection rates, viscosity, and rock properties. This model will account for both particle release and suspension deposition. By use of this model, a methodology is proposed to derive model parameters from routine injection tests by inverse analysis. The proposed model presents the characteristic behavior of unconsolidated formation during fluid injection and the possible effect of injection parameters on downhole-permeability evolution.

Carbon Brake Friction Model Parameter Identification Using Genetic Algorithms

1995 ◽  
Author(s):  
Roger C. von Doenhoff ◽  
Robert J. Streifel ◽  
Robert J. Marks
Keyword(s):  
Genetic Algorithm ◽  
Genetic Algorithms ◽  
Surface Temperature ◽  
Parameter Identification ◽  
Friction Model ◽  
Carbon Surface ◽  
Model Parameters ◽  
Model Parameter ◽  
Brake Pressure ◽  
Model Parameter Identification

Abstract A model of the friction characteristics of carbon brakes is proposed to aid in the understanding of the causes of brake vibration. The model parameters are determined by a genetic algorithm in an attempt to identify differences in friction properties between brake applications during which vibration occurs and those during which there is no vibration. The model computes the brake torque as a function of wheelspeed, brake pressure, and the carbon surface temperature. The surface temperature is computed using a five node temperature model. The genetic algorithm chooses the model parameters to minimize the error between the model output and the torque measured during a dynamometer test. The basics of genetic algorithms and results of the model parameter identification process are presented.

Analytical and experimental analysis of axial force generated by a drive shaft system

2020 ◽  
Vol 234 (4) ◽  
pp. 691-706 ◽  
Author(s):  
Huayuan Feng ◽  
Subhash Rakheja ◽  
Wen-Bin Shangguan
Keyword(s):  
Dynamic Model ◽  
Axial Force ◽  
Friction Model ◽  
Drive Shaft ◽  
Contact Model ◽  
Model Parameters ◽  
Shaft System ◽  
Multibody Dynamic ◽  
Generated Axial Force ◽  
Operational Factors

The drive shaft system with a tripod joint is known to cause lateral vibration in a vehicle due to the axial force generated by various contact pairs of the tripod joint. The magnitude of the generated axial force, however, is related to various operating factors of the drive shaft system in a complex manner. The generated axial force due to a drive shaft system with a tripod joint and a ball joint was experimentally characterized considering ranges of operational factors, namely, the input toque, the shaft rotational speed, the articulation angle, and the friction. The data were analyzed to establish an understanding of the operational factors on the generated axial force. Owing to the observed significant effects of all the factors, a multibody dynamic model of the drive shaft system was formulated for predicting generated axial force under different operating conditions. The model integrated the roller–track contact model and the velocity-based friction model. Based on a quasi-static finite element model, a new methodology was proposed for identifying the roller–track contact model parameters, namely, the contact stiffness and force index. To further enhance the calculation accuracy of the multibody dynamic model, a new methodology for identifying the friction model parameters and the force index was proposed by using the measured data. The validity of the model was demonstrated by comparing the model-predicted and measured magnitudes of generated axial force for the ranges of operating factors considered. The results showed that the generated axial force of the drive shaft system can be calculated more accurately and effectively by using the identified friction and contact parameters in the paper.

The role of geomechanical modeling in the measurement and understanding of geophysical data collected during carbon sequestration

2021 ◽  
Vol 40 (6) ◽  
pp. 413-417
Author(s):  
Chunfang Meng ◽  
Michael Fehler
Keyword(s):  
Pore Pressure ◽  
Fault Location ◽  
Mechanical Response ◽  
Fluid Pressure ◽  
Geophysical Data ◽  
Fluid Injection ◽  
Coupled Flow ◽  
Cap Rock ◽  
Stress And Deformation ◽  
Pressure Changes

As fluids are injected into a reservoir, the pore fluid pressure changes in space and time. These changes induce a mechanical response to the reservoir fractures, which in turn induces changes in stress and deformation to the surrounding rock. The changes in stress and associated deformation comprise the geomechanical response of the reservoir to the injection. This response can result in slip along faults and potentially the loss of fluid containment within a reservoir as a result of cap-rock failure. It is important to recognize that the slip along faults does not occur only due to the changes in pore pressure at the fault location; it can also be a response to poroelastic changes in stress located away from the region where pore pressure itself changes. Our goal here is to briefly describe some of the concepts of geomechanics and the coupled flow-geomechanical response of the reservoir to fluid injection. We will illustrate some of the concepts with modeling examples that help build our intuition for understanding and predicting possible responses of reservoirs to injection. It is essential to understand and apply these concepts to properly use geomechanical modeling to design geophysical acquisition geometries and to properly interpret the geophysical data acquired during fluid injection.

Role of fracture opening in triggering microseismicity observed during hydraulic fracturing

Geophysics ◽  
2019 ◽  
Vol 84 (3) ◽  
pp. KS105-KS118 ◽  
Author(s):  
Himanshu Barthwal ◽  
Mirko van der Baan
Keyword(s):  
Hydraulic Fracturing ◽  
Pore Pressure ◽  
Material Balance ◽  
Crack Tip ◽  
Hydrocarbon Reservoirs ◽  
Fluid Injection ◽  
Low Permeability ◽  
Stress Shadow ◽  
Pressure Diffusion ◽  
Microseismic Events

Hydraulic fracturing in low-permeability hydrocarbon reservoirs creates/reactivates a fracture network leading to microseismic events. We have developed a simplified model of the evolution of the microseismic cloud based on the opening of a planar fracture cavity and its effect on elastic stresses and pore pressure diffusion during fluid injection in hydraulic fracturing treatments. Using a material balance equation, we compute the crack tip propagation over time assuming that the hydraulic fracture is shaped as a single penny-shaped cavity. Results indicate that in low-permeability formations, the crack tip propagates much faster than the pore pressure diffusion front thereby triggering the microseismic events farthest from the injection domain at any given time during fluid injection. We use the crack tip propagation to explain the triggering front observed in distance versus time plots of published microseismic data examples from hydraulic fracturing treatments of low-permeability hydrocarbon reservoirs. We conclude that attributing the location of the microseismic triggering front purely to pore pressure diffusion from the injection point may lead to incorrect estimates of the hydraulic diffusivity by multiple orders of magnitude for low-permeability formations. Moreover, the opening of the fracture cavity creates stress shadow zones perpendicular to the principal fracture walls in which microseismic triggering due to the elastic stress perturbations is suppressed. Microseismic triggering in this stress shadow region may be attributed mainly to pore pressure diffusion. We use the width, instead of the longest size, of the microseismic cloud to obtain an enhanced diffusivity measure, which may be useful for subsequent production simulations.

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