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Separation and imaging of seismic diffractions using plane-wave decomposition


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Summary We use the simulated plane wave section method to separate specular reflections and diffraction events. We show that plane wave sections naturally separate specular and diffracted events and allow us to use plane-wave distruction filters to suppress specular events resulting in plane-wave sections of diffractions. A synthetic example demonstrates the effectiveness of our method in imaging faults and small-scale discontinuities.
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Separation and imaging of seismic diffractions using plane-wave decomposition
M. Turhan Taner, Rock Solid Images, Sergey Fomel, University of Texas at Austin, and Evgeny Landa, OPERA
We use the simulated plane wave section method to
separate specular reflections and diffraction events. We
show that plane wave sections naturally separate specular
and diffracted events and allow us to use plane-wave
distruction filters to suppress specular events resulting in
plane-wave sections of diffractions
. A synthetic example
demonstrates the effectiveness of our method in imaging
faults and small-scale discontinuities.
Seismic reflection data contain two types of coherent
events generated from the subsurface discontinuities:
specular reflections and diffractions. Specular reflections
are the ones being used conventionally to interpret
structural and stratigraphic features of the subsurface.
Diffractions have been neglected by most researchers.
Specular reflections are generated by interfaces with
impedance contrasts. Diffractions are generated by local
discontinuities when they act like point sources. These
point sources become active as soon as the direct wave hits
them. Presence of diffractions can indicate faults or
fractures, which is important in carbonate environments,
where locating fractures and their orientation is the
objective of seismic interpretation.
The idea of using diffractions in seismic imaging is not
new. Harlan et al. (1984) used forward modeling and local
slant stacks for extracting velocity information from
diffractions. Landa et al., (1987), Landa and Keydar (1998)
used common-diffraction-point sections for imaging of
diffraction energy and detecting local heterogeneities. In
this paper, we take a different route by attempting to
separate diffraction events before imaging. In a companion
paper (Fomel et al, 2006), we discuss separation and
imaging of diffractions appearing on post-stack sections.
The separation is based on application of plane-wave
destruction filters (Claerbout, 1992 ; Fomel, 2002). An
analogous idea, but with an implementation based on
multidimensional prediction-error filters, was previously
discussed by Claerbout (1994).
In this paper, we use the simulated plane wave section
method (Taner, 1976; Shultz and Claerbout, 1978) to
separate specular reflections and diffraction events. We
show that the plane wave sections naturally separate
specular and diffracted events and allow us to use the
plane-wave distruction filter to suppress specular events
resulting in plane-wave sections of diffractions. We use a
synthetic example to confirm the proposed method.
Let us consider behavior of a plane reflector and a point
diffraction scatterer in case of a point source shot record.
Specular reflection and diffraction from the point scatterer
appear on the seismic record in the form of hyperbolas.
That is both of them behave like a point source, as depicted
schematically in Figure 1. While the
specular interface
acts like a mirror, we will see the point source in its
position, the diffractor is activated at the moment
when the direct wave arrives and the scatterer point acts as
a source in depth.
Figure 1. Reflections from a plane reflector and a
diffractor, illuminated by a point source. a) Depth section,
b) Corresponding time section
2401SEG/New Orleans 2006 Annual Meeting
Prestack diffraction separation
If we activate a plane wave source, the reflected event from
a plane specular reflector creates a plane wave, while the
point diffractor behaves the same way as in the previous
case and acts like a point source. (Figure 2)
Figure 2. Plane reflector and a diffractor reflections , as
illuminated by a plane source wave: a) Depth section,
b) Corresponding time section.
To generate plane wave sections from a point source
seismic data we invoke two basic laws: superposition and
reciprocity. Reciprocity helps us exchange receiver and
source positions. By the superposition we can combine
different seismic records together to simulate plane-wave
records as if all the sources were exploded simultaneously.
Plane wave decomposition (Taner, 1976) can be
schematically described as follows. Taking one common
shot record and summing the traces horizontally without
any time delay we simulate a trace which we would obtain
if we exploded simultaneously many sources at the receiver
locations and record the reflected data at the source
position. Repeating this procedure for several shot records
we can simulate plane-wave source record. When we deal
with marine case (single end observation geometry) the
cable end creates an edge effect: semi spherical wave field,
we wish to attenuate. To do it, we can use the reciprocity
principle and create an artificial split-spread shot record by
sorting the data to CMP domain, replicating the CMP data
to the opposite sign offsets, and sorting it back to the shot
When we sum a split spread shot record horizontally, we
simulate a plane wave propagating vertically downward at
the inception. If we shift the traces linearly before
summation, we generate a
dipping plane wave. By
repeating summations with various dips, we actually
generate a τ-p section corresponding to our shot record, or
the Radon transform estimate. There
are many procedures
to compute the Radon transform (Gardner and Lu, 1991),
and we do not discuss them here.
More details about plane-wave decomposition are
described by Yilmaz and Taner (1994). A section of a
constant plane-wave slope p illuminates the subsurface
with a specific angle at the surface. On these constant p
sections we will have specular reflections appear as quasi-
linear continuous events and diffracted waves will appear
in the quasi-hyperbolic shaped traveltimes (Green’s
functions). We can now use the plane-wave destruction
filter (Fomel, 2002) to suppress the specular events and to
obtain a section containing mainly diffracted events and
residual specular reflection energy. Since the resulting
traces are Radon transformed traces, their S/N ratio should
be better than the original traces in the time domain. The
scattering objects (faults, fractures etc.) will be imaged on
the migrated (time or depth) common p sections.
In summary, our flow for wavefield separation is:
1) Generate split spread common source records;
2) Plane-wave decompose each common source
3) Sort into constant p sections;
4) Plane-wave destruction filter on constant p
5) Velocity analysis for migration;
6) Migrate individual p sections and then sum to
produce a prestack migration image.
Figure 3a shows a synthetic single end shot gather for a
model containing numerous sharp structural discontinuities
producing numerous diffraction events. To perform plane-
wave decomposition for shot records we constructed a split
spread observation geometry using the reciprocity as it is
described above (Figure 3b). Figure 4a shows plane-wave
decomposed shot gather and Figure 4b illustrates the same
shot gather reconstructed by an inverse Radon transform.
2402SEG/New Orleans 2006 Annual Meeting
Prestack diffraction separation
Repeating plane-wave decomposition for all shot records
we obtain common p section for entire line. Figure 5 and 6
show two common p sections for different p parameter: 0,
0.5. Applying the plane-wave distruction filter to each of
the total wavefield sections (left) we obtain the
corresponding sections containing mostly diffraction
energy (right). It is interesting to observe that some of the
separated events in the deeper part of the sections are
actually not diffractions but triplications of the propagating
plane wave caused by lateral velocity variations.
Figure 3. Single ended (left) and split-spread (right) shot
Figure 4. Radon transformed (left) and reconstructed by
inverse Radon transform shot gather
Figure 5. Common p (p=0) section of the total wavefield
(left) and after wavefield separation (right).
Figure 6. Common p (p=0.5) section of the total wavefield
(left) and after wavefield separation (right)
Sorting back to shot domain and applying inverse Radon
transform we obtain seismic records containing diffraction
events and residual specular reflection energy. These
records now can be used for velocity model estimating,
time or depth imaging and should emphasize sharp
discontinuities of the subsurface. Figure 7 shows prestack
depth migrated image of the total wavefield (a) and
“diffractions only” components (b). Most of the scattering
objects which are masked on the conventional section (a)
can be observed on the “diffractions only” section (b).
2403SEG/New Orleans 2006 Annual Meeting
Prestack diffraction separation
Figure 7. Prestack depth migration of the full wave-field (a)
and the separated diffractions (b).
The objective of this paper is to show that plane-wave
constant p sections contain diffraction patterns that directly
obey the wave equation together with specular reflectors. In
contrast to point source sections, plane-wave sections
contain specular events that appear as simply shaped
laterally continuous events. Diffracted events appear in the
form of focusing operators with a delay equal to the travel
time from the source wave origin to the point scatterer.
This observation allowed us to develop a method for
diffraction separation and imaging based on applying
plane-wave destruction filtering on plane-wave sections.
Separated and imaged diffractions can provide valuable
information about small-scale subsurface features such as
faults, fractures, rough salt boundaries, channels, etc.
Although we show only a 2-D example in this paper, our
method is applicable to 3-D plane-wave decompositions
such as those recently described by Zhang et al (2005).
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Geophysics, 70, E21-E28.
2404SEG/New Orleans 2006 Annual Meeting
Note: This reference list is a copy-edited version of the reference list submitted by the
author. Reference lists for the 2006 SEG Technical Program Expanded Abstracts have
been copy edited so that references provided with the online metadata for each paper will
achieve a high degree of linking to cited sources that appear on the Web.
Claerbout, J. F., 1992, Earth sounding analysis: Processing versus inversion: Blackwell
Scientific Publications, Inc.
———, 1994, Applications of two- and three-dimensional filtering: 64th Annual
International Meeting, SEG, Expanded Abstracts, 1572–1575.
Fomel, S., 2002, Applications of plane-wave destruction filters: Geophysics,
67, 1946–
Fomel, S., E. Landa, and M. T. Taner, 2006, Post-stack velocity analysis by separation
and imaging of seismic diffractions: Presented at the 76th Annual International
Meeting, SEG.
Gardner, G. F., and L. Lu, eds., 1991, Slant-stack processing: SEG.
Harlan, W. S., J. F. Claerbout, and F. Rocca, 1984, Signal/noise separation and velocity
estimation: Geophysics,
49, 1869–1880.
Landa, E., and S. Keydar, 1998, Seismic monitoring of diffracted images for detection of
local heterogeneities: Geophysics,
63, 1093.
Landa, E., V. Shtivelman, and B. Gelchinsky, 1987, A method for detection of diffracted
waves on common-offset sections: Geophysical Prospecting,
35, 359-373.
Schultz, P. S., and J. F. Claerbout, 1978, Velocity estimation and downward continuation
by wavefront synthesis: Geophysics,
43, 691–714.
Taner, M. T., 1976, Simplan: Similated plane-wave exploration: 46th Annual
International Meeting, SEG, Expanded Abstracts, 186–187.
Yilmaz, O., and M. T. Taner, 1994, Discrete plane-wave decomposition by least-mean-
square-error method: Geophysics,
59, 973–982.
Zhang, Y., J. Sun, C. Notfors, S. H. Gray, L. Chernis, and J. Young, 2005, Delayed-shot
3D depth migration: Geophysics,
70, E21–E28.
2405SEG/New Orleans 2006 Annual Meeting
... Previous studies have confirmed that the diffraction wave field can be better described for small-scale geological bodies (Gallop & Hron, 1998;Klem-Musatov, 2008;Taner, 2006;Zhu, 2010;Ivan et al., 2013); when the spatial scale of the local geological body is close to or smaller than the resolution of seismic reflection data (generally less than λ/4), the diffraction wave data separated from the seismic data can be used to finely describe small-scale geological bodies. Therefore, the predecessors according to the dynamics and wave characteristics of the diffraction wave field, different diffraction wave extraction methods are proposed (Xie, 2021; Liang, 2019). ...
... If the intrusive position is close to the top of the reservoir, the intrusive rock and the top of the reservoir will form wave field interference, and it is difficult to effectively identify this part of the intrusive rock with conventional attributes. The diffraction wave extraction technology can effectively separate the diffraction wave field caused by the intrusive rock from the reflected wave field on the top of the carbonate reservoir and finally achieve the purpose of fine description of the spatial distribution of the intrusive rock [14,15]. ...
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Aiming at the difficulties in the fine description of small- and medium-scale geological bodies in storage, this paper develops a method for describing geological bodies using diffracted wave data and systematically explains the effectiveness of the method through model calculations. Finally, this method is applied to fractures. In the fine description of the type of reservoir and the intrusive rock mass of the reservoir, two diffraction wave attribute analysis methods are used to achieve the fine description of the distribution law of the above small-scale geological bodies. The principal component analysis method is proposed to extract the diffraction from the seismic wave field. Information, the wave field is separated through the kinematics and dynamics of the diffraction wave, and the obtained diffraction wave field better reflects the distribution law of small-scale geological bodies. Verified by examples, the diffraction wave analysis method can be more refined and a comprehensive description of the distribution of small-scale geological bodies.
... For instance, the focusing-muting-focusing strategy on prestack common-shot gathers is used to improve diffraction image resolution (Khaidukov et al., 2004). The plane-wave destruction filter is used by Taner et al. (2006) to suppress specular reflection events and extract diffractions. The wavefront attributes have been utilized to separate diffraction and improve diffraction velocity spectra modeling quality (Bakhtiari Rad et al., 2018). ...
... Several authors have tried different approaches such as least-squares RTM (LS-RTM) which uses iterative least-squares inversion to correct migration errors [17][18][19] or combinations of the leastsquares inverse problem and RTM [20][21][22][23][24]. While LS-RTM produces sidelobes around reflectors and high-wavenumber migration artifacts, its results in the image resolution, reducing artifacts, and compensating amplitudes are auspicious.. Seismic diffraction is another approach that has been used for imaging faults and steep dips, yielding improved subsurface imaging with better representations of structural topographies at high spatial resolutions [25][26][27][28]. Also, Bashir et al. [29,30] have shown that this approach is particularly useful to improve the results in 0 to 10 Hz and 50 to 60 Hz frequency bands. ...
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The Rakhine Basin in the northeastern Bay of Bengal is an active field in hydrocarbon exploration and development. It contains fault structures and steeply sloping stratigraphic reservoirs, both primary features of interest for hydrocarbon exploration that needs to be accurately imaged to improve the interpretation of seismic data and facilitate the accurate identification of features of interest. Although faults are an indicator of possible hydrocarbon traps, they are difficult to identify in seismic images using traditional stack or prestack time migration due to the rather complex behaviors of wave propagation. On the other hand, prestack depth migration (PSDM) can significantly improve the accuracy of seismic images, especially of complex subsurface structures such as faults, folds, overthrusts, and salt domes. Among the various PSDM approaches, reverse time migration (RTM) has been shown to be the most powerful. Here, we show how PSDM-RTM can significantly improve the representation of fault structures and steeply dipping structures in seismic images from field data collected in Rakhine Basin, which is characterized by complex geology including stratigraphic and strati-structural traps as well as complex channel systems. Typically, these structures appear heavily blurred and are difficult to identify using normal stack and prestack time migration. We demonstrate that they become clearer and easier to detect with the PSDM–RTM approach, making this approach particularly suitable for seismic interpretations of geologically complex areas within the context of hydrocarbon prospecting.
... The plane-wave destruction (PWD) method is a practical diffractions separating method. Taner et al. (2006) and Kong et al. (2012Kong et al. ( , 2017 used the PWD filters in the plane-wave domain to separate reflections with linear characteristics and diffractions with hyperbolic characteristics. Zhao et al. (2016a,b) used the sparse inversion method to extract diffractions to identify discontinuous and heterogeneous geological information after PWD filtering. ...
... Because of the great significance of using diffraction for imaging small-scale discontinuous objects, a range of methods for separating diffractions from the rest of the recorded wavefield have become available (Berkovitch et al., 2009;Kanasewich & Phadke, 1988;Krey, 1952;Kunz, 1960;Pant et al., 1992;Taner et al., 2006). The diffraction-separation methods can be classified into two categories according to the differences regarding the separation domains. ...
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Seismic responses generated from small-scale dis-continuous geologic structures are encoded into weak diffractions. Thus, diffraction imaging has great potential for providing high-resolution structural and stratigraphic sections for interpreters. Because diffractions behave as weak signals and are easily masked by strong reflections, diffraction separation from specular reflections is a necessary processing step for high-resolution diffraction imaging. However, most diffraction-separation methods are performed in the post-stack or common-offset domains, while ignoring prestack information or requiring perfect data acquisition. Furthermore , prestack separation methods usually consider the combination of two diffraction-separation technologies; thus, the corresponding results depend on several different parameters. To deal with these problems, we propose a plane-wave destruction (PWD)-based workflow for prestack diffraction separation in the shot domain that uses the differences in the local slopes between reflections and diffractions. The new diffraction-separation work-flow extends the application of PWD from the poststack to the prestack domain without additional technology, and the shot-domain data have the advantage of the waveform consistency and continuity. The plane-wave trace prediction algorithm derived from plane-wave equation is considered for predicting and flattening strong reflections in the shot domain. A plane-wave filter based on regularized slope prediction is used for attenuating flat reflections and enhancing weak diffractions. Synthetic and field examples demonstrate the feasibility of the proposed workflow in identifying and locating small-scale discontinuous bodies.
... Then, diffraction waves will be imaged individually. The indirect diffraction imaging method mainly includes commonoffset gather methods (Landa et al., 1987), common diffraction point profile methods (Kanasewich and Phadke, 1988), common-shot record methods (Nowak, 2005;Khaidukov et al., 2004;Moser and Howard, 2010), plane wave record methods (Taner et al., 2006) and others (Papziner and Nick, 1998;Bansal and Imhof, 2005). ...
Diffractions comprise the seismic response of subsurface geological discontinuities and thus can provide detailed geological information during 3-D seismic exploration. The separation of weak diffractions from specular reflections is challenging, especially when the diffractions and reflections have similar kinematical characteristics in the 3-D pre-stack case. Conventional separation methods often estimate the local slope based on optimization or the Hilbert transform, which directly depends on the distribution behaviour of seismic events and may lead to the aliasing effects of the hyperbolic reflected and diffracted slopes in the shot domain. In this study, a different method is employed: local slopes are parametrized and constrained to the normal moveout velocity and ray parameter, which can distinguish reflections and diffractions in the shot domain and enhance the stability and accuracy of local slopes. Interestingly, when the receiver line and the geological edge are coplanar, the corresponding edge diffractions and reflections exhibit extremely similar behaviour, rendering them indistinguishable. Considering this phenomenon, a 3-D pre-stack diffraction separation strategy is proposed based on the estimation of the local slopes in two orthogonal directions. Thus, the accurate local slope can be used for plane-wave destruction when separating diffractions in the 3-D pre-stack domain. Synthetic and field data applications demonstrate that the proposed separation strategy is effective and can obtain high-quality diffraction wavefields for detecting the subsurface discontinuous structure.
Diffractions possess the potential to reveal subsurface discontinuities, including faults, collapsed columns, and the rough edges of the salt body. We propose a novel diffraction separation method that flattens the dominant reflections at first and then identifies the diffraction wavefields through an orthogonal polynomial transform. Based on the plane-wave assumption and local slope, the reflection events can be predicted and flattened using plane-wave differential equations. To enhance the stability of the flattening process, a sliding window algorithm, and three finite-difference forms were adopted. As the dominant coherent event, a reflection often corresponds to low-order coefficients in the orthogonal polynomial transform. To better preserve the diffraction energy, a time-varying order threshold was used when removing the dominant reflections. Two field data applications are presented to demonstrate the feasibility and effectiveness of the proposed diffraction separation strategy.
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For 3D seismic imaging in structurally complex areas, the use of migration by wavefield extrapolation has become widespread. By its very nature, this family of migration methods operates on data sets that satisfy a wave equation in the context of a single, physically realizable field experiment, such as a common-shot record. However, common-shot migration of data recorded over dipping structures requires a migration aperture much larger than the recording aperture, resulting in extra computations. A different type of wave-equation record, the response to a linear or planar source; can be synthesized from all the common-shot records. Synthesizing these records from common-shot records involves slant-stack processing, or applying delays to the. various shots; we call these records delayed-shot records. Delayed-shot records don't suffer from the aperture problems of common-shot records since their recording aperture is the length of the seismic survey. Consequently, delayed-shot records hold potential for efficient, accurate imaging by wavefield extrapolation. We present a formulation of delayed-shot migration in 2D and 3D (linear sources) and its application to 3D marine streamer data. This formulation includes a discussion of sampling theory issues associated with the formation of delayed-shot records. For typical marine data, 2D and 3D delayed-shot migration can be significantly more efficient than common-shot migration. Synthetic and real data examples show that delayed-shot migration produces images comparable to those from common-shot migration.
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A signal/noise separation must recognize the lateral coherence of geologic events and their statistical predictability before extracting those components most useful for a particular process, such as velocity analysis. Events with recognizable coherence we call signal; the rest we term noise. Let us define 'focusing' as increasing the statistical independence of samples with some invertible, linear transform L. By the central limit theorem, focused signal must become more non-Gaussian. A measure F defined from cross entropy measures non-Gaussianity from local histograms of an array, and thereby measures focusing. Local histograms of the transformed data and of transformed, artificially incoherent data provide enough information to estimate the amplitude distributions of transformed signal and noise; errors only increase the estimate of noise. These distributions allow the recognition and extraction of samples containing the highest percentage of signal. Estimating signal and noise iteratively improves the extractions of each. After the removal of bed reflections and noise, F will determine the best migration velocity for the remaining diffractions. Slant stacks map lines to points, greatly concentrating continuous reflections. We extract samples containing the highest concentration of this signal, invert, and subtract from the data, leaving diffractions and noise. Next, we migrate with many velocities, extract focused events, and invert. Then we find the least-squares sum of these events best resembling the diffractions in the original data. Migration of these diffractions maximizes F at the best velocity. We successfully extract diffractions and estimate velocities for a window of data containing a growth fault. A spatially variable least-squares superposition allows spatially variable velocity estimates. Local slant stacks allow a laterally adaptable extraction of locally linear events. For a stacked section we successfully extract weak signal with highly variable coherency from behind strong Gaussian noise. Unlike normal moveout (NMO), wave-equation migration of a few common-midpoint (CMP) gathers can image the skewed hyperbolas of dipping reflectors correctly. Short local slant stacks along midpoint will extract reflections with different dips. A simple Stolt (1978) (f-k)type algorithm migrates these dipping events with appropriate dispersion relations. This migration may then be used to extract events containing velocity information over offset. Offset truncations become another removable form of noise. One may remove non-Gaussian noise from shot gathers by first removing the most identifiable signal, then estimating the samples containing the highest percentage of noise. Those samples containing a significant percentage of signal may be zeroed; what remains represents the most identifiable noise and may be subtracted from the original data. With this procedure we successfully remove ground roll and other noise from a shot (field) gather.
The recording of a point source wavefield can be decomposed into a set of plane‐wave components, each corresponding to different angles of propagation. Such plane‐wave seismograms have a far simpler structure than the spherical waves of the point source records, which makes them desirable in many steps of seismic data processing such as predictive deconvolution, migration, inversion, etc. The implementation of the plane‐wave decomposition requires the computation of the Radon transform in the discrete data domain. A straightforward application of the integral solutions to geophysical problems fails to compensate for the sampled and limited aperture nature of the actual data. In this paper, we give a new method in which the x-t domain is shown to relate to the p-τ domain by a linear system of equations in the time‐space domain. An iterative least‐mean‐square‐error method is introduced to solve the set of equations. This method is combined with a unique method of alias suppression which uses the reasonable range of dips possible at a given (x, t) location and acts as interpolation of the x-t data. This combination improves the initial estimates and speeds up convergence. Our transform is independent of the number of plane‐waves and selected ray parameter range. We present synthetic and real data examples to demonstrate the accuracy and robustness of the method. The examples are compared against results using the generalized Radon transform approach used by Beylkin (1987) and against conventional slant stack.
The summary was misstated in the “Annual Meeting Selections” category of “This Issue of GEOPHYSICS” on page 1SO. We apologize for any inconvenience caused by this error.
A wave stack is any stack over a common shot or geophone gather in which the moveout is independent of time. It synthesizes a particular wavefront by superposition of the many spherical wavefronts of raw data. Unlike the common midpoint stack, wave stacks retain the important property of being the sampling of a wave field and, as such, permit wave-equation treatment of formerly difficult or impossible problems. Seismic sections of field data generated by wave stacks that synthesized slanted downgoing plane waves showed a similarity in appearance to the common midpoint stacks. In signal-to-noise ratio they lay between the single offset section and the midpoint stack. The angle selectivity of the slanted plane-wave stacks permitted detection of a reflector that was not visible on either the midpoint stack or the raw gathers. Simple velocity estimation in slant frame coordinates differs only in detail from standard frame coordinates. Because of the wave field character of data that have been slant plane-wave stacked, wave-equation techniques can be used to generalize migration and velocity estimation to regions in which exists a strong lateral velocity inhomogeneity within the distance of a cable spread. 27 figures.
Diffracted waves contain valuable information regarding both the structure and composition of the media they are in. In seismic data processing, however, these waves are usually regarded as noise. In this paper, we present an attempt to use scattered/diffracted waves for the detection of local heterogeneities. The method is based on the detection of diffracted waves by concentrating the signal amplitudes from diffracting points on the seismic section. This is done using a correlation procedure that enhances the amplitude of the seismic signal at the location of the diffractors on the common-diffraction-point section (D-section), The new local time correction for diffraction traveltime curve parameterization is based on the radius of curvature of the diffracted wavefront and near-surface velocity. We use the idea of seismic monitoring for detection and delineating local objects which may occur within the subsurface resulting from human activity or fast geological processes. The method consists of continuous repetition of seismic experiments above an investigated area, constructing D-sections, and comparing the images obtained.
ABSTRACTA method of detection of diffracted waves on common-offset sections is proposed. The method utilizes the main kinematic and dynamic properties of the diffracted waves. The detection algorithm is defined by an automatic procedure including phase correlation of the diffracted waves and the application of certain statistical criteria. This procedure enables us to make decisions with regard to the presence of the diffracted waves and also to estimate parameters of the scattering objects. The method is applied to synthetic and field data and, even for a relatively low signal-to-noise ratio, it gives reliable results.