Seismic Wave Simulation in Fractured Media

2021 ◽  
Author(s):  
Houzhu Zhang ◽  
Jiaxuan Li ◽  
Abdulmohsen Ali
Keyword(s):  
Wave Propagation ◽  
Fractured Reservoirs ◽  
Forward Modeling ◽  
Source Rocks ◽  
Reservoir Performance ◽  
Amplitude Versus Offset ◽  
Seismic Detection ◽  
Potential Applications ◽  
Subsurface Fractures ◽  
Global Energy Supply

Abstract Fractured reservoirs, including unconventional fields, are important in global energy supply, particularly for carbonate source rocks. Fractures can influence subsurface fluid flow and the stress state of a reservoir. The knowledge about the existence of fractures, their spatial distributions, and orientations can help us optimize well productivity and reservoir performance. Seismic detection of subsurface fractures provides important measurements to remotely image field-scale fractures. In developing such technology, forward modeling of the seismic response from fractures in the reservoir provides an important alternate tool for imaging subsurface fractures. In this paper, we implement a seismic modeling algorithm which can simulate 3D wave propagation in an arbitrary background media with imbedded fractures. During modeling, the fractures are added to the background medium by linear slip theory. Examples demonstrated the impacts of fractures on the wave propagation patterns for both PP and PS waves. We also investigate the amplitude versus offset (AVO) effects caused by fractures in a layer media and lay out potential applications of forward modeling in the inversion of fracture parameters and the estimation of fluid contents.

Wave propagation improvement in two-dimensional bond-based peridynamics model

2021 ◽  
pp. 095440622098555
Author(s):  
Reza Alebrahim ◽  
Pawel Packo ◽  
Mirco Zaccariotto ◽  
Ugo Galvanetto
Keyword(s):  
Wave Propagation ◽  
Dynamic Performance ◽  
Numerical Dispersion ◽  
Motion Modeling ◽  
Minimization Method ◽  
Irregular Wave ◽  
Point Collocation ◽  
Potential Applications ◽  
Non Local ◽  
Set Up

In this study, methods to mitigate anomalous wave propagation in 2-D Bond-Based Peridynamics (PD) are presented. Similarly to what happens in classical non-local models, an irregular wave transmission phenomenon occurs at high frequencies. This feature of the dynamic performance of PD, limits its potential applications. A minimization method based on the weighted residual point collocation is introduced to substantially extend the frequency range of wave motion modeling. The optimization problem, developed through inverse analysis, is set up by comparing exact and numerical dispersion curves and minimizing the error in the frequency-wavenumber domain. A significant improvement in the wave propagation simulation using Bond-Based PD is observed.

Tunable Wave Propagation in Granular Crystals by Altering Lattice Network Topology

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Raj Kumar Pal ◽  
Robert F. Waymel ◽  
Philippe H. Geubelle ◽  
John Lambros
Keyword(s):  
Wave Propagation ◽  
Network Topology ◽  
Stable Equilibrium ◽  
Primary Chain ◽  
First Case ◽  
Granular Crystals ◽  
Potential Applications ◽  
Wave Tailoring ◽  
Lattice Network ◽  
Granular Crystal

We develop a framework for wave tailoring by altering the lattice network topology of a granular crystal consisting of spherical granules in contact. The lattice topology can alternate between two stable configurations, with the spherical granules of the lattice held in stable equilibrium in each configuration by gravity. Under impact, the first configuration results in a wave with rapidly decaying amplitude as it propagates along a primary chain, while the second configuration results in a solitary wave propagating along the primary chain with no decay. The mechanism to achieve such tunability is by having energy diverted to the granules adjacent to the primary chain in the first case but not the second. The tunable design of the proposed network is validated using both numerical simulations and experiments. In terms of potential applications, the proposed bistable lattice network can be viewed either as a wave attenuator or as a device that allows higher amplitude wave propagation in one direction than in the opposite direction. The lattice is analogous to a crystal phase transformation due to the change in atomic configurations, leading to the change in properties at the macroscale.

scholarly journals Analysis of GPR Wave Propagation Using CUDA-Implemented Conformal Symplectic Partitioned Runge-Kutta Method

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Hongyuan Fang ◽  
Jianwei Lei ◽  
Man Yang ◽  
Ziwei Li
Keyword(s):  
Wave Propagation ◽  
Forward Modeling ◽  
Electromagnetic Response ◽  
Acceleration Technique ◽  
Efficient Calculation ◽  
Dense Grid ◽  
Runge Kutta ◽  
Processor Unit ◽  
The Stability ◽  
Ground Penetrating

Accurate forward modeling is of great significance for improving the accuracy and speed of inversion. For forward modeling of large sizes and fine structures, numerical accuracy and computational efficiency are not high, due to the stability conditions and the dense grid number. In this paper, the symplectic partitioned Runge-Kutta (SPRK) method, surface conformal technique, and graphics processor unit (GPU) acceleration technique are combined to establish a precise and efficient numerical model of electromagnetic wave propagation in complex geoelectric structures, with the goal of realizing a refined and efficient calculation of the electromagnetic response of an arbitrarily shaped underground target. The results show that the accuracy and efficiency of ground-penetrating radar (GPR) forward modeling are greatly improved when using our algorithm. This provides a theoretical basis for accurately interpreting GPR detection data and accurate and efficient forward modeling for the next step of inversion imaging.

Seismic modeling in viscoelastic media

Geophysics ◽  
1993 ◽  
Vol 58 (1) ◽  
pp. 110-120 ◽  
Author(s):  
José M. Carcione
Keyword(s):  
Wave Propagation ◽  
Viscoelastic Medium ◽  
Polynomial Interpolation ◽  
Superposition Principle ◽  
Forward Modeling ◽  
Memory Storage ◽  
Three Dimensions ◽  
Bright Spot ◽  
Viscoelastic Media ◽  
Standard Linear

Anelasticity is usually caused by a large number of physical mechanisms which can be modeled by different microstructural theories. A general way to take all these mechanisms into account is to use a phenomenologic model. Such a model which is consistent with the properties of anelastic media can be represented mechanically by a combination of springs and dash‐pots. A suitable system can be constructed by the parallel connection of several standard linear elements and is referred to as the general standard linear solid rheology. Two relaxation functions that describe the dilatational and shear dissipation mechanisms of the medium are needed. This model properly describes the short and long term behaviors of materials with memory and is the basis for describing viscoelastic wave propagation. This work presents two‐dimensional (2-D) and three‐dimensional (3-D) forward modeling in linear viscoelastic media. The theory implements Boltzmann’s superposition principle based on a spectrum of relaxation mechanisms in the time‐domain equation of motion by the introduction of the memory variables. The algorithm uses a polynomial interpolation of the evolution operator for time integration and the Fourier pseudospectral method for computation of the spatial derivatives. This scheme has spectral accuracy for band‐limited functions with no temporal or spatial dispersion, a very important fact in anelastic wave propagation. Examples are given of how to pose typical problems of viscoelastic forward modeling for geophysical problems in two and three dimensions. A model separating an elastic medium of a viscoelastic medium with similar elastic moduli but different attenuations shows that the interface generates appreciable reflected energy. A second example computes the response of a single interface in the presence of highly dissipative sandstone lenses, properly simulating the anelasticity of direct and converted P‐ and S‐waves. A common‐shot reflection survey over a gas cap reservoir indicates that attenuation significantly affects the bright spot response. 3-D viscoelastic modeling requires twice the memory storage of 3-D viscoacoustic modeling when one dissipation mechanism is used for each wave mode. Simulation in a 3-D homogeneous viscoelastic medium shows how the anelastic characteristics of the different modes can be controlled independently. The result of this simulation is compared to the analytical solution indicating sufficient accuracy for many applications.

scholarly journals WAVE PROPAGATION ANALYSIS IN A PRESSURE-WAVE-REFRIGERATOR

2005 ◽  
Vol 19 (28n29) ◽  
pp. 1747-1750 ◽  
Author(s):  
W. ZHAO ◽  
Z. L. JIANG ◽  
H. R. YU ◽  
T. SAITO ◽  
K. TAKAYAMA
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Pressure Wave ◽  
Simple Structure ◽  
Operation Condition ◽  
Expansion Waves ◽  
Independent Analysis ◽  
Propagation Analysis ◽  
Potential Applications ◽  
Operation Parameters

Pressure wave refrigerators (PWR) refrigerate the gas through periodical expansion waves. Due to its simple structure and robustness, PWR may have many potential applications if the efficiency becomes competitive with existing alternative devices. In order to improve the efficiency, the characteristics of wave propagation in a PWR are studied by experiment, numerical simulation and theoretical analysis. Based on the experimental results and numerical simulation, a simplified model is suggested, which includes the assumptions of flux-equilibrium and conservation of the free energy. This allows the independent analysis of the operation parameters and design specifics. Furthermore, the optimum operation condition can be deduced. Some considerations to improve the PWR efficiency are also given.

Model-based amplitude versus offset and azimuth inversion for estimating fracture parameters and fluid content

Geophysics ◽  
2017 ◽  
Vol 82 (2) ◽  
pp. M1-M17 ◽  
Author(s):  
Jiao Xue ◽  
Hanming Gu ◽  
Chengguo Cai
Keyword(s):  
Seismic Data ◽  
Shear Fracture ◽  
Influencing Factor ◽  
Fractured Reservoirs ◽  
Fracture Density ◽  
Inversion Algorithm ◽  
Fluid Content ◽  
Fracture Parameters ◽  
Amplitude Versus Offset ◽  
Amplitude Versus

The normal-to-shear fracture compliance ratio is commonly used as a fluid indicator. In the seismic frequency range, the fluid indicator lies between the values for isolated fluid-filled fractures and dry fractures, and it is not easy to discriminate the fluid content. Assuming that the fracture surfaces are smooth, we use [Formula: see text], with [Formula: see text] and [Formula: see text] representing the normal fracture weakness of the saturated and dry rock, to indicate fluid types, and to define a fluid influencing factor. The fluid influencing factor is sensitive to the fluid properties, the aspect ratio of the fractures, and the frequency. Conventionally, the amplitude versus offset and azimuth (AVOA) inversion is formulated in terms of the contrasts of the fracture weaknesses across the interface, assuming that the fractures are vertical with the same symmetry axis. We consider fractures with arbitrary azimuths, and develop a method to estimate fracture parameters from wide-azimuth seismic data. The proposed AVOA inversion algorithm is tested on real 3D prestack seismic data from the Tarim Basin, China, and the inverted fracture density show good agreement with well log data, except that there are some discrepancies for one of the fractured reservoir sections. The discrepancies can be ascribed to neglect of the dip angle for the tilted fractures and the conjugate fracture sets, and to the validity of the linear-slip model. The fractured reservoirs are expected to be liquid saturated, under the assumption of smooth fractures. Overall, the inverted fracture density and fluid influencing factor can be potentially used for better well planning in fractured reservoirs and quantitatively estimating the fluid effects.

scholarly journals Integration of Seismic Anisotropy and Reservoir Performance Data for Characterization of Naturally Fractured Reservoirs Using Discrete Feature Network Models

2005 ◽  
Vol 8 (02) ◽  
pp. 132-142 ◽  
Author(s):  
Robert Will ◽  
Rosalind A. Archer ◽  
William S. Dershowitz
Keyword(s):  
Seismic Data ◽  
Elastic Anisotropy ◽  
Fractured Reservoirs ◽  
Seismic Attributes ◽  
Performance Data ◽  
Naturally Fractured Reservoirs ◽  
Fracture System ◽  
Reservoir Performance ◽  
Naturally Fractured ◽  
System Characteristics

Summary This paper proposes a method for quantitative integration of seismic(elastic) anisotropy attributes with reservoir-performance data as an aid in characterizing systems of natural fractures in hydrocarbon reservoirs. This method is demonstrated through application to history matching of reservoir performance using synthetic test cases. Discrete-feature-network (DFN) modeling is a powerful tool for developing fieldwide stochastic realizations of fracture networks in petroleum reservoirs. Such models are typically well conditioned in the vicinity of the wellbore through incorporation of core data, borehole imagery, and pressure-transient data. Model uncertainty generally increases with distance from the borehole. Three-dimensional seismic data provide uncalibrated information throughout the interwell space. Some elementary seismic attributes such as horizon curvature and impedance anomalies have been used to guide estimates of fracture trend and intensity (fracture area per unit volume) in DFN modeling through geostatistical calibration with borehole and other data. However, these attributes often provide only weak statistical correlation with fracture-system characteristics. The presence of a system of natural fractures in a reservoir induces elastic anisotropy that can be observed in seismic data. Elastic attributes such as azimuthally dependent normal move out velocity (ANMO), reflection amplitude vs. azimuth (AVAZ), and shear-wave birefringence can be inverted from 3D-seismicdata. Anisotropic elastic theory provides physical relationships among these attributes and fracture-system properties such as trend and intensity. Effective-elastic-media models allow forward modeling of elastic properties for fractured media. A technique has been developed in which both reservoir-performance data and seismic anisotropic attributes are used in an objective function for gradient-based optimization of selected fracture-system parameters. The proposed integration method involves parallel workflows for effective elastic and effective permeability media modeling from an initial DFN estimate of the fracture system. The objective function is minimized through systematic updates of selected fracture-population parameters. Synthetic data cases show that3D-seismic attributes contribute significantly to the reduction of ambiguity in estimates of fracture-system characteristics in the interwell rock mass. The method will benefit enhanced-oil-recovery (EOR) program planning and management, optimization of horizontal-well trajectory and completion design, and borehole-stability studies. Introduction Anisotropy and heterogeneity in reservoir permeability present challenges during the development of hydrocarbon reserves in naturally fractured reservoirs. Predicting primary reservoir performance, planning development drilling or EOR programs, completion design, and facilities design all require accurate estimates of reservoir properties and the predictions of future reservoir behavior computed from such estimates. Over the history of naturally-fractured-reservoir development, many methods have been used to characterize fracture systems and their effect on fluid flow in the reservoir. These include the use of geologic surface-outcrop analogs; core, single-well, and multiwell pressure-transient analysis; borehole-imaging logs; and surface and borehole seismic observations. To date, efforts to integrate seismic data into the workflow for characterization of naturally fractured reservoirs have been focused on the use of post-stack data. CDP stacking of seismic data takes advantage of redundancy in seismic data sets for the attenuation of noise. Unfortunately, CDP stacking also eliminates valuable information about spatial and orientational variations in the data. Such variations are often related to fracture-system characteristics. CDP-stacked seismic data are typically used to define the main structural elements of the reservoir. Fracture density has been correlated successfully with horizon curvature determined from seismic horizons. Seismic attributes frequently can be correlated with reservoir properties such as shale fraction, which often correlates with fracture-population statistics. Acoustic impedance computed from seismic data frequently exhibits dim spots in the presence of fractures.

Power Density Distribution in Subsurface Fractures Due to an Energized Steel Well-casing Source

2019 ◽  
Vol 24 (2) ◽  
pp. 285-297
Author(s):  
G. Didem Beskardes ◽  
W. Anderson McAliley ◽  
Mohsen Ahmadian ◽  
David T. Chapman ◽  
Chester J. Weiss ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Contrast Agents ◽  
Power Density ◽  
Fractured Reservoirs ◽  
Current Source ◽  
Hydraulic Fractures ◽  
Distributed Sensors ◽  
Fracture Width ◽  
Dc Excitation ◽  
Subsurface Fractures

Robust in situ power harvesting underlies the realization of embedded wireless sensors for monitoring the physicochemical state of subsurface engineered structures and environments. The use of electromagnetic (EM) contrast agents in hydraulically fractured reservoirs, in coordination with completion design of wells, offers a way to transmit energy to remotely charge distributed sensors and interrogate fracture width, extent, and fracture-stage cross-communication. The quantification of available power in fracture networks due to energized steel-cased wells is crucial for such sensor designs; however, this has not been clarified via numerical modeling in the limit of Direct Current (DC). This paper presents a numerical modeling study to determine the EM characteristics of a subsurface system that is based on a highly instrumented field observatory. We use those realistic field scenarios incorporating geometry and material properties of contrast agents, the wellbore, and the surrounding geologic environment to estimate volumetric power density near the wellbore and within hydraulic fractures. The numerical modeling results indicate that the highest power densities are mainly focused around the wellbore excited by a point current source and the fracture boundary. Using DC excitation, the highest power density in the fracture is at the fracture tip. The relatively high-power density on the order of tens of mW/m 3 at the vicinity of the wellbore and at fracture tips suggests that remote charging of sensor devices may be readily possible. Simulation results also show that the region of the highest power density can be significantly increased when the EM source is located inside a conductive fracture, which may lead to a promising deployment strategy for embedded micro-sensors in geologic formations.

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