Effect of main frequencies on characterizing fault damage zones using forward modeling and attribute of variance

2020 ◽  
Vol 8 (4) ◽  
pp. SP157-SP165
Author(s):  
Yangpu Chen ◽  
Zonghu Liao ◽  
Li-Yun Fu ◽  
Gang Zhou ◽  
Liang Xu ◽  
...  
Keyword(s):  
Damage Zone ◽  
Low Frequency ◽  
Forward Modeling ◽  
Seismic Attributes ◽  
Frequency Effect ◽  
Fracture Density ◽  
Internal Structures ◽  
Fault Structures ◽  
Scattering Noise ◽  
40 Hz

Faulting processes have created large damage zones with complex structures in the field; however, estimating the width and geometry of such fault structures in the subsurface is challenging due to a lack of data. Seismic attributes (e.g., coherence and variance) from seismic surveys have been used for the characterization of faults, but most cases do not detail the effectiveness of this approach. By using forward modeling and the associated seismic attributes of variance, four fault models of idealized damage zones are characterized and the frequency effect is evaluated on the width estimation of fault damage zones in the subsurface. The main results indicate that (1) the general geometric pattern of damage zones could be identified by using simulated amplitude and seismic variance with main frequencies of 10, 25, and 40 Hz; (2) the estimated widths of damage zones at a low frequency of 10 Hz are larger (up to twofold) than those at frequencies of 25 and 40 Hz; for large damage zones (>400 m), the width is best estimated by a frequency of 25 Hz; and (3) scattering noise and diffraction around the fault are found in data at a high frequency of 40 Hz, which results in width overestimation of the damage zones by approximately 17%. The internal structures are difficult to distinguish as scattering noise and chaotic reflections dominate seismic signals. More factors that may influence the accuracy of damage zone width estimation via seismic attributes, include the bedding thickness, fracture density, and velocity. An in-depth understanding of this approach is useful in the application of seismic variance to characterize fault damage zones that may significantly control the fluid migration in the subsurface.

Analyze the Seismic Attributes in HSX Volcanic Fracture Based on Forward Modeling

2014 ◽  
Vol 556-562 ◽  
pp. 899-902
Author(s):  
Yong Wang
Keyword(s):  
Fractured Reservoirs ◽  
Forward Modeling ◽  
Seismic Attributes ◽  
Fractured Media ◽  
Two Dimensional ◽  
Fracture Density ◽  
Seismic Attribute ◽  
Difference Wave ◽  
Depth Migration ◽  
Fracture Models

This paper uses the Hassan Carboniferous fractured reservoirs as the goal, firstly it analyses the reservoir characteristics of the cracks. On this basis, it uses two-dimensional random fractured media modeling method to build three different fracture models with different fracture parameters (fracture density, dip and speed). Then it uses finite difference wave equation forward and pre-stack depth migration processing of these models, and analyses seismic attribute of the migrated data, finally it finds a variety of seismic attributes sensitive to cracks, lays the foundation for fracture prediction with the seismic multi-attributes.

scholarly journals Priming effects in the recognition of simple and complex words and pseudowords

2018 ◽  
Vol 39 (2) ◽  
pp. 198-222
Author(s):  
Miguel Lázaro ◽  
Víctor Illera ◽  
Javier Sainz
Keyword(s):  
Word Recognition ◽  
Low Frequency ◽  
Morphological Processing ◽  
Orthographic Processing ◽  
Frequency Effect ◽  
Experimental Conditions ◽  
Priming Effects ◽  
The Third ◽  
Complex Words ◽  
Intense Debate

AbstractWhether morphological processing of complex words occurs beyond orthographic processing is a matter of intense debate. In this study, morphological processing is examined by presenting complex words (brujería -> brujo –witchcraft -> witch), as well as simple (brujaña->brujo) and complex pseudowords (brujanza ->brujo), as primes in three masked lexical decision tasks. In the first experiment, the three experimental conditions facilitated word recognition in comparison to the control condition, but no differences emerged between them. Given the importance of the surface frequency effect observed, a second experiment was conducted. The results fully replicate those observed in the first one, but this time with low frequency targets. In the third experiment, vowels were removed from the stems of primes to reduce the orthographic overlap between primes and targets and, therefore, the influence of the embedded stem effect. The results show facilitative effects only for complex words. However, paired comparisons show no differences between experimental conditions. The overall results show the central role played by the processing of stems in visual word recognition and are explained in terms of current models of morphological processing.

Poststack impedance inversion considering the diffractive component of the wavefield

Geophysics ◽  
2020 ◽  
Vol 85 (1) ◽  
pp. R11-R28 ◽  
Author(s):  
Kun Xiang ◽  
Evgeny Landa
Keyword(s):  
Specular Reflection ◽  
Low Frequency ◽  
Velocity Model ◽  
Forward Modeling ◽  
Small Scale ◽  
Fracture Detection ◽  
Frequency Model ◽  
New Approach ◽  
Impedance Inversion ◽  
Diffraction Imaging

Seismic diffraction waveform energy contains important information about small-scale subsurface elements, and it is complementary to specular reflection information about subsurface properties. Diffraction imaging has been used for fault, pinchout, and fracture detection. Very little research, however, has been carried out taking diffraction into account in the impedance inversion. Usually, in the standard inversion scheme, the input is the migrated data and the assumption is taken that the diffraction energy is optimally focused. This assumption is true only for a perfectly known velocity model and accurate true amplitude migration algorithm, which are rare in practice. We have developed a new approach for impedance inversion, which takes into account diffractive components of the total wavefield and uses the unmigrated input data. Forward modeling, designed for impedance inversion, includes the classical specular reflection plus asymptotic diffraction modeling schemes. The output model is composed of impedance perturbation and the low-frequency model. The impedance perturbation is estimated using the Bayesian approach and remapped to the migrated domain by the kinematic ray tracing. Our method is demonstrated using synthetic and field data in comparison with the standard inversion. Results indicate that inversion with taking into account diffraction can improve the acoustic impedance prediction in the vicinity of local reflector discontinuities.

IP interpretation in environmental investigations

Geophysics ◽  
2002 ◽  
Vol 67 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Lee D. Slater ◽  
David Lesmes
Keyword(s):  
Field Experiments ◽  
Low Frequency ◽  
Environmental Parameters ◽  
Clay Content ◽  
Chemistry Laboratory ◽  
Frequency Effect ◽  
Resistivity Method ◽  
Surface Polarization ◽  
Capacitive Properties ◽  
Diffusion Polarization

The induced polarization (IP) response of rocks and soils is a function of lithology and fluid conductivity. IP measurements are sensitive to the low‐frequency capacitive properties of rocks and soils, which are controlled by diffusion polarization mechanisms operating at the grain‐fluid interface. IP interpretation typically is in terms of the conventional field IP parameters: chargeability, percentage frequency effect, and phase angle. These parameters are dependent upon both surface polarization mechanisms and bulk (volumetric) conduction mechanisms. Consequently, they afford a poor quantification of surface polarization processes of interest to the field geophysicist. A parameter that quantifies the magnitude of surface polarization is the normalized chargeability, defined as the chargeability divided by the resistivity magnitude. This parameter is proportional to the quadrature conductivity measured in the complex resistivity method. For nonmetallic minerals, the quadrature conductivity and normalized chargeability are closely related to lithology (through the specific surface area) and surface chemistry. Laboratory and field experiments were performed to determine the dependence of the standard IP parameters and the normalized chargeability on two important environmental parameters: salinity and clay content. The laboratory experiments illustrate that the chargeability is strongly correlated with the sample resistivity, which depends on salinity, porosity, saturation, and clay content. The normalized chargeability is shown to be independent of the sample resistivity and it is proportional to the quadrature conductivity, which is directly related to the surface polarization processes. Laboratory‐derived relationships between conductivity and salinity, and normalized chargeability and clay content, are extended to the interpretation of 1‐D and 2‐D field‐IP surveys. In the 2‐D survey, the apparent conductivity and normalized chargeability data are used to segment the images into relatively clay‐free and clay‐rich zones. A similar approach can eventually be used to predict relative variations in the subsurface clay content, salinity and, perhaps, contaminant concentrations.

Ceiling Construction Low-Frequency Noise Issues

2013 ◽  
Vol 649 ◽  
pp. 277-280
Author(s):  
Petra Berková ◽  
Pavel Berka
Keyword(s):  
Spectral Analysis ◽  
Low Frequency ◽  
Sound Insulation ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Frequency Tone ◽  
The Impact ◽  
40 Hz

Through the use of a spectral analysis of the source of noise – person’s movement over the ceiling construction – it was found out that in this kind of noise distinctive low-frequency tone components occur (31,5 - 40 Hz) which is beyond the evaluation area of the impact sound insulation of the ceiling construction, s. [2], [3].

scholarly journals QUANTITATIVE ANALYSIS OF DEFORMATION ALONG THE FAULT DAMAGE ZONE OF THE KLIMATIA THRUST (NW GREECE, IONIAN ZONE)

2001 ◽  
Vol 34 (4) ◽  
pp. 1643
Author(s):  
A. Kostakioti ◽  
P. Xypolias ◽  
S. Kokkalas ◽  
T. Doutsos
Keyword(s):  
Hanging Wall ◽  
Damage Zone ◽  
Deformation Pattern ◽  
Fracture System ◽  
Fracture Density ◽  
Fracture Orientation ◽  
Transport Direction ◽  
Structural Fracture ◽  
Fault Damage Zone ◽  
Northwestern Greece

In this study, we present structural, fracture orientation and fracture density (FD) data in order toquantify the deformation pattern of a damage zone that form around the slip plane of a large scalethrust fault which is located on the Ionian zone (External Hellenides) in northwestern Greece. Structuralanalysis showed at least two major deformation stages as indicated by the presence of refolding,backthrusting and break-back faulting. The fracture orientation analysis revealed three mainfracture systems, a dominant conjugate fracture system which is perpendicular to the transport direction(NW-to NNW trending sets), a conjugate fracture system trending parallel to the transport direction(ENE-trending conjugate sets) and a third diagonal conjugate fracture system (WNW andNNE trending sets). Resulting fracture density-distance diagrams display a decrease of total fracturedensity away from the studied fault, which is largely heterogeneous and irregular on both footwalland hanging wall. The conjugate fracture system trending perpendicular to the transport directionhas the dominant contribution to the accumulation of total fracture density. Based on theseresults we suggest that the observed heterogeneous and irregular distribution of fracture densityfashioned during the second deformation stage and is attributed to the formation of backthrusts andbreak-back thrust faults.

scholarly journals Track Dynamic Response At Low Frequencies – Dominant Frequencies

2015 ◽  
Vol 15 (2) ◽  
Author(s):  
Milan Moravčík ◽  
Martin Moravčík
Keyword(s):  
Dynamic Response ◽  
Moving Load ◽  
Low Frequency ◽  
Track Structure ◽  
Dynamic Effects ◽  
Low Frequencies ◽  
Frequency Area ◽  
Dominant Frequencies ◽  
40 Hz

Abstract The paper is devoted dynamic effects in the track structure - the quasi-static excitation due to moving load, as the important source for the response of track components in the low frequency area (0 Hz < f < 40 Hz). The low-frequency track (the rail) response is associated with periodicity of wheel sets, bogies, and carriages of passage trains, The periodicity of track loading is determined by so called dominant frequencies f(d) at a position x of the track.

Nonword repetition and levels of abstraction in phonological knowledge

2006 ◽  
Vol 27 (4) ◽  
pp. 577-581 ◽  
Author(s):  
Benjamin Munson
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Nonword Repetition ◽  
Chronological Age ◽  
Frequency Effect ◽  
Vocabulary Size ◽  
Levels Of Abstraction ◽  
Opposite Pattern ◽  
The Difference ◽  
Restriction Of Range

Susan Gathercole's Keynote Article (2006) is an impressive summary of the literature on nonword repetition and its relationship to word learning and vocabulary size. When considering research by Mary Beckman, Jan Edwards, and myself, Gathercole speculates that our finding of a stronger relationship between vocabulary measures and repetition accuracy for low-frequency sequences than for high-frequency sequences is due to differences in the range of the two measures. In our work on diphone repetition (e.g., Edwards, Beckman, & Munson, 2004; Munson, Edwards, & Beckman, 2005) we tried to increase the range in our dependent measures by coding errors on a finer grained scale than simple correct/incorrect scoring would allow. Moreover, restriction of range does not appear to be the driving factor in the relationship between vocabulary size and the difference between high- and low-frequency sequence repetition accuracy (what we call the frequency effect) in at least one of our studies (Munson et al., 2005). When the children with the 50 lowest mean accuracy scores for high-frequency sequences were examined, vocabulary size accounted for 10.5% of the variance in the frequency effect beyond what was accounted for by chronological age. When the 50 children with the highest mean accuracy scores for high-frequency sequences were examined (a group in which the range of high-frequency accuracy scores was more compressed, arguably reflecting ceiling effects), an estimate of vocabulary size accounted for only 6.9% of the frequency effect beyond chronological age. The associated β coefficient was significant only at the α<0.08 level. This is the opposite pattern than Gathercole's argument would predict.

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