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1
Subarsyah, Subarsyah, and Yulinar Firdaus. "PERBAIKAN CITRA PENAMPANG SEISMIK MENGGUNAKAN METODE COMMON REFLECTION SURFACE : APLIKASI TERHADAP DATA SEISMIK PERAIRAN WAIGEO." JURNAL GEOLOGI KELAUTAN 13, no. 2 (February 16, 2016): 119. http://dx.doi.org/10.32693/jgk.13.2.2015.267.
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Kenampakan struktur geologi dan kontinuitas reflektor pada penampang seismik seringkali tidak teridentifikasi ketika data seismik di stack menggunakan metode stacking konvensional, terutama untuk data dengan jumlah fold coverage yang kecil. Data seismik Puslitbang Geologi Kelautan yang diperoleh pada Mei 2015, di Perairan Timur Pulau Waigeo, memiliki fold coverage yang relatif rendah sekitar 20. Untuk meningkatkan kualitas penampang seismik pada data ini perlu diterapkan metode Common Reflection Surface(CRS) sehingga interpretasi struktur geologi lebih mudah dan kontinuitas reflektor lebih baik. Metode ini diaplikasikan terhadap data seismik lintasan 6 dan 37. Penerapan metode CRS memberikan perbaikan pada citra penampang seismik terutama pada bagian basement akustik dan kontinuitas reflektor. Metode ini memberikan citra penampang seismik yang relatif lebih baik dibandingkan metode stacking konvensional karena metode CRS melibatkan trace seismik dari CDP di sekitarnya sesuai dengan besar parameter aperturnya. Kata kunci CRS Stack, CRS Attribut dan Paraxial Geological structure and reflector continuity on seismic section are often not clearly identified when the seismic data stacked use conventional stacking, especially seismic data with small fold coverage. Seismics data of Puslitbang Geologi Kelautan, that have been acquired on Mei 2015,in eastern part of Waigeo Island, have small number of fold coverage about 20. To enhance quality of seismic section on this data, it is necessary to apply Common Reflection Surface (CRS) method, in order to make geological structure interpretation easier dan better reflector continuity. This method applied to seismic data line 6 and 37. This application gives enhancement to seismic section especially at acoustic basement and reflector continuity. CRS method gives better seismic section than conventional stacking due to stacking process that involve seismic trace around the CDP along its aperture size. Keywords: CRS Stack, CRS Attribut and Paraxial
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Skopintseva, Lyubov, Milana Ayzenberg, Martin Landrø, Tatyana Nefedkina, and Arkady M. Aizenberg. "Long-offset AVO inversion of PP reflections from plane interfaces using effective reflection coefficients." GEOPHYSICS 76, no. 6 (November 2011): C65—C79. http://dx.doi.org/10.1190/geo2010-0079.1.
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A conventional amplitude variation with offset (AVO) inversion is based on geometrical seismics which exploit plane-wave reflection coefficients to describe the reflection phenomenon. Widely exploited linearizations of plane-wave coefficients are mostly valid at pre-critical offsets for media with almost flat and weak-contrast interfaces. Existing linearizations do not account for the seismic frequency range by ignoring the frequency content of the wavelet, which is a strong assumption. Plane-wave reflection coefficients do not fully describe the reflection of seismic waves at near-critical and post-critical offsets, because reflected seismic waves are typically generated by point sources. We propose an improved approach to AVO inversion, which is based on effective reflection coefficients (ERCs). ERCs generalize plane-wave coefficients for seismic waves generated by point sources and therefore more accurately describe near-critical and post-critical reflections where head waves are generated. Moreover, they are frequency-dependent and incorporate the local curvatures of the wavefront and the reflecting interface. In our study, we neglect the effect of interface curvature and demonstrate the advantages of our approach on synthetic data for a simple model with a plane interface separating two isotropic half-spaces. A comparison of the inversion results obtained with our approach and the results from an AVO inversion method based on the exact plane-wave reflection coefficient suggests that our method is superior, in particular for long-offset ranges which extend to and beyond the critical angle. We thus propose that long offsets can be successfully exploited in an AVO inversion under the correct assumption about the reflection coefficient. Such long-offset AVO inversion shows the potential of outperforming a conventional moderate-offset AVO inversion in the accuracy of estimated model parameters.
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Minato, Shohei, Toshifumi Matsuoka, Takeshi Tsuji, Deyan Draganov, Jürg Hunziker, and Kees Wapenaar. "Seismic interferometry using multidimensional deconvolution and crosscorrelation for crosswell seismic reflection data without borehole sources." GEOPHYSICS 76, no. 1 (January 2011): SA19—SA34. http://dx.doi.org/10.1190/1.3511357.
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Crosswell reflection method is a high-resolution seismic imaging method that uses recordings between boreholes. The need for downhole sources is a restrictive factor in its application, for example, to time-lapse surveys. An alternative is to use surface sources in combination with seismic interferometry. Seismic interferometry (SI) could retrieve the reflection response at one of the boreholes as if from a source inside the other borehole. We investigate the applicability of SI for the retrieval of the reflection response between two boreholes using numerically modeled field data. We compare two SI approaches — crosscorrelation (CC) and multidimensional deconvolution (MDD). SI by MDD is less sensitive to underillumination from the source distribution, but requires inversion of the recordings at one of the receiver arrays from all the available sources. We find that the inversion problem is ill-posed, and propose to stabilize it using singular-value decomposition. The results show that the reflections from deep boundaries are retrieved very well using both the CC and MDD methods. Furthermore, the MDD results exhibit more realistic amplitudes than those from the CC method for downgoing reflections from shallow boundaries. We find that the results retrieved from the application of both methods to field data agree well with crosswell seismic-reflection data using borehole sources and with the logged P-wave velocity.
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Guo, Feng, Changshuan Ji, Shenghua Lai, and Lei Zhang. "A method of establishing high-resolution isochronous stratigraphic framework in 3D seismic data volume." Stratigraphy 20, no. 2 (2023): 143–54. http://dx.doi.org/10.29041/strat.20.2.04.
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The establishment of a high-frequency sequence stratigraphic framework (short-term cycles) is the basis of seismic sedimentology research, which provides a new way to establish a high-resolution isochronous stratigraphic framework using 3D-seismic data. The linear interpolation between reference seismic reflections is used to establish a high-resolution isochronous stratigraphic framework (stratal slices). By carefully calibrating time-depth relationships, a corresponding relationship between short-term cycle (high-frequency cycle) interfaces and stratal slices is created. Five reference seismic reflections correspond to maximum flood surfaces. The results show that 311 isochronous stratal slices are formed in the 90 degree phase of the 3D seismic data set. Reference seismic reflection does not change with frequency. The event axis of reference for isochronous seismic reflection often corresponds to the most obvious isochronous interfaces. This method can establish a high-resolution isochronous stratigraphic framework in areas lacking drilling data in a 3D seismic data set. When geological dating data is available, the stratal slices can be further calibrated to absolute geological time, and a paleogeological map can be constructed from the seismic data set. This case study also illustrates the theoretical and practical significance of this method.
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JING, Xi-Li, Chang-Chun YANG, and Shi-Qing WANG. "An Improved Seismic Reflection Tomographic Method." Chinese Journal of Geophysics 50, no. 6 (November 2007): 1588–94. http://dx.doi.org/10.1002/cjg2.1179.
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Saatçilar, Ruhi, and Nezihi Canitez. "A method of ground‐roll elimination." GEOPHYSICS 53, no. 7 (July 1988): 894–902. http://dx.doi.org/10.1190/1.1442526.
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Amplitude‐ and frequency‐modulated wave motion constitute the ground‐roll noise in seismic reflection prospecting. Hence, it is possible to eliminate ground roll by applying one‐dimensional, linear frequency‐modulated matched filters. These filters effectively attenuate the ground‐roll energy without damaging the signal wavelet inside or outside the ground roll’s frequency interval. When the frequency bands of seismic reflections and ground roll overlap, the new filters eliminate the ground roll more effectively than conventional frequency and multichannel filters without affecting the vertical resolution of the seismic data.
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Murphy, Gary E., and Samuel H. Gray. "Manual seismic reflection tomography." GEOPHYSICS 64, no. 5 (September 1999): 1546–52. http://dx.doi.org/10.1190/1.1444658.
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Prestack depth migration needs a good velocity model to produce a good image; in fact, finding the velocity model is one of the goals of prestack depth migration. Migration velocity analysis uses information produced by the migration to update the current velocity model for use in the next migration iteration. Several techniques are currently used to estimate migration velocities, ranging from trial and error to automatic methods like reflection tomography. Here, we present a method that combines aspects of some of the more accurate methods into an interactive procedure for viewing the effects of residual normal moveout corrections on migrated common reflection point (CRP) gathers. The residual corrections are performed by computing traveltimes along raypaths through both the current velocity model and the velocity model plus suggested model perturbations. The differences between those sets of traveltimes are related to differences in depth, allowing the user to preview the approximate effects of a velocity change on the CRP gathers without remigrating the data. As with automatic tomography, the computed depth differences are essentially backprojected along raypaths through the model, yielding a velocity update that flattens the gathers. Unlike automatic tomography, in which an algebraic inverse problem is solved by the computer for all geologic layers simultaneously, our method estimates shallow velocities before proceeding deeper and requires substantial user intervention, both in flattening individual CRP gathers and in deciding the appropriateness of the suggested velocity updates in individual geologic units.
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Wu, Xinming, and Sergey Fomel. "Least-squares horizons with local slopes and multigrid correlations." GEOPHYSICS 83, no. 4 (July 1, 2018): IM29—IM40. http://dx.doi.org/10.1190/geo2017-0830.1.
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Most seismic horizon extraction methods are based on seismic local reflection slopes that locally follow seismic structural features. However, these methods often fail to correctly track horizons across discontinuities such as faults and noise because the local slopes can only correctly follow laterally continuous reflections. In addition, seismic amplitude or phase information is not used in these methods to compute horizons that follow a consistent phase (e.g., peaks or troughs). To solve these problems, we have developed a novel method to compute horizons that globally fit the local slopes and multigrid correlations of seismic traces. In this method, we first estimate local reflection slopes by using structure tensors and compute laterally multigrid slopes by using dynamic time warping (DTW) to correlate seismic traces within multiple laterally coarse grids. These coarse-grid slopes can correctly correlate reflections that may be significantly dislocated by faults or other discontinuous structures. Then, we compute a horizon by fitting, in the least-squares sense, the slopes of the horizon with the local reflection slopes and multigrid slopes or correlations computed by DTW. In this least-squares system, the local slopes on the fine grid and the multiple coarse-grid slopes will fit a consistent horizon in areas without lateral discontinuities. Across laterally discontinuous areas where the local slopes fail to correctly correlate reflections and mislead the horizon extraction, the coarse-grid slopes will help to find the corresponding reflections and correct the horizon extraction. In addition, the multigrid correlations or slopes computed by dynamic warping can also assist in computing phase-consistent horizons. We apply the proposed horizon extraction method to multiple 2D and 3D examples and obtain accurate horizons that follow consistent phases and correctly track reflections across faults.
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Lin, Peng, Suping Peng, Xiaoqin Cui, Wenfeng Du, and Chuangjian Li. "Effective diffraction separation using the improved optimal rank-reduction method." GEOPHYSICS 87, no. 3 (February 23, 2022): V169—V182. http://dx.doi.org/10.1190/geo2021-0326.1.
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Seismic diffractions encoding subsurface small-scale geologic structures have great potential for high-resolution imaging of subwavelength information. Diffraction separation from the dominant reflected wavefields still plays a vital role because of the weak energy characteristics of the diffractions. Traditional rank-reduction (RR) methods based on the low-rank assumption of reflection events have been commonly used for diffraction separation. However, these methods using truncated singular-value decomposition (TSVD) suffer from the problem of reflection-rank selection by singular-value spectrum analysis, especially for complicated seismic data. In addition, the separation problem for the tangent wavefields of reflections and diffractions is challenging. To alleviate these limitations, we have developed an effective diffraction separation strategy using an improved optimal RR (ORR) method to remove the dependence on the reflection rank and improve the quality of separation results. The improved RR method adaptively determines the optimal singular values from the input signals by directly solving an optimization problem that minimizes the Frobenius-norm difference between the estimated and exact reflections instead of the TSVD operation. This improved method can effectively overcome the problem of reflection-rank estimation in the global and local RR methods and adjusts to the diversity and complexity of seismic data. The adaptive data-driven algorithms indicate good performance in terms of the trade-off between high-quality diffraction separation and reflection suppression for the ORR operation. Applications of our strategy to synthetic and field examples demonstrate the superiority of diffraction separation in detecting and revealing subsurface small-scale geologic discontinuities and inhomogeneities.
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Zhang, Jin, Yanguo Wang, David C. Nobes, Guangnan Huang, and Hongxing Li. "Deep seismic reflection data interpretation using balanced filtering method." GEOPHYSICS 82, no. 5 (September 1, 2017): N43—N49. http://dx.doi.org/10.1190/geo2016-0061.1.
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Inverse [Formula: see text] filtering can perform energy compensation and phase correction of seismic reflection data, but it has an instability problem due to its high-pass characteristics. Although improved methods, such as gain-limited inverse [Formula: see text] filtering and stabilized inverse [Formula: see text] filtering, overcome the instability to some extent, they are not suitable for compensating deep seismic reflection events with weak energy. Focusing on the enhancement of deep seismic events, we have developed a balanced filtering method based on the ratio of the phase-compensated signal to its analytic signal counterpart. The method is insensitive to the depth of seismic records, and it can make shallow and deep seismic records visible simultaneously. When tested on synthetic data and real seismic data, compared with other methods, the balanced filtering method improves the amplitude strength of the deep reflection events and the continuity of shallow and deep seismic events effectively, which makes the deep reflection data easier to interpret.
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Dell, Sergius, and Dirk Gajewski. "Common-reflection-surface-based workflow for diffraction imaging." GEOPHYSICS 76, no. 5 (September 2011): S187—S195. http://dx.doi.org/10.1190/geo2010-0229.1.
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Imaging of diffractions is a challenge in seismic processing. Standard seismic processing is tuned to enhance reflections. Separation of diffracted from reflected events is frequently used to achieve an optimized image of diffractions. We present a method to effectively separate and image diffracted events in the time domain. The method is based on the common-reflection-surface-based diffraction stacking and the application of a diffraction-filter. The diffraction-filter uses kinematic wavefield attributes determined by the common-reflection-surface approach. After the separation of seismic events, poststack time-migration velocity analysis is applied to obtain migration velocities. The velocity analysis uses a semblance based method of diffraction traveltimes. The procedure is incorporated into the conventional common-reflection-surface workflow. We apply the procedure to 2D synthetic data. The application of the method to simple and complex synthetic data shows promising results.
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IWATSUKI, Osamu, Masaaki TABATA, Ryuji KUBOTA, Masakazu FURUTANI, and Oshie TAZAWA. "Shallow Seismic Reflection Method for Geotechnical Surveys." Journal of the Japan Society of Engineering Geology 38, no. 6 (1998): 359–69. http://dx.doi.org/10.5110/jjseg.38.359.
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Kim, Sooyoon, Soon Jee Seol, Joongmoo Byun, and Seokmin Oh. "Extraction of diffractions from seismic data using convolutional U-net and transfer learning." GEOPHYSICS 87, no. 2 (January 27, 2022): V117—V129. http://dx.doi.org/10.1190/geo2020-0847.1.
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Diffraction images can be used for modeling reservoir heterogeneities at or below the seismic wavelength scale. However, the extraction of diffractions is challenging because their amplitude is weaker than that of overlapping reflections. Recently, deep-learning (DL) approaches have been used as a powerful tool for diffraction extraction. Most DL approaches use a classification algorithm that classifies pixels in the seismic data as diffraction, reflection, noise, or diffraction with reflection and takes whole values for the classified diffraction pixels. Thus, these DL methods cannot extract diffraction energy from pixels for which diffractions are masked by reflections. We have developed a DL-based diffraction extraction method that preserves the amplitude and phase characteristics of diffractions. Through the systematic generation of a training data set using synthetic modeling based on t-distributed stochastic neighbor embedding analysis, this technique extracts not only faint diffractions but also diffraction tails overlapped by strong reflection events. We also determine that the DL model pretrained with a basic synthetic data set can be applied to seismic field data through transfer learning. Because the diffractions extracted by our method preserve the amplitude and phase, they can be used for velocity model building and high-resolution diffraction imaging.
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Miller, Richard D., and Don W. Steeples. "A shallow seismic reflection survey in basalts of the Snake River Plain, Idaho." GEOPHYSICS 55, no. 6 (June 1990): 761–68. http://dx.doi.org/10.1190/1.1442888.
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The objective of this feasibility study was to determine if the seismic reflection method could help to optimize placement of water‐quality monitoring wells near a radioactive storage facility. Seismic reflections from depths less than 30 m were recorded along a 500 m long line over a basalt, rhyolite, and sedimentary sequence in the Snake River Plain. Some shallow reflections at 40 to 50 ms on the field files are of exceptional quality with frequency exceeding 150 Hz. Reflections and refractions from selected seismograms along the line possess vastly different normal‐moveout (NMO) and apparent velocities as well as wavelet characteristics. Extreme variations in quality, seismic character, and reflector geometries observed on seismograms give the appearance of varying geologic settings and are uncommon for such short distances. Severe surgical muting was necessary for accurate velocity and statics analyses. The seismic reflection data show apparent structural lows in a sedimentary layer sandwiched between basalt flows. Interpreted structural lows must be verified by drilling before a monitoring plan can be fully developed. Similar shallow reflection surveys could also be used to improve deeper conventional seismic data in this and other basaltic terrain.
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Pu, Duan, Dunli Chen, and Yinfeng Dong. "Comparative Analysis of Application of Seismic Wave Reflection Method in Advanced Geological Prediction." Journal of Architectural Research and Development 7, no. 2 (March 29, 2023): 27–39. http://dx.doi.org/10.26689/jard.v7i2.4756.
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Seismic wave reflection method is an advanced geophysical detection method in tunnel geological prediction. It is more sensitive and effective in detecting geological anomalies such as fault fracture zone and karst. In order to verify the prediction efficacy and accuracy of the seismic wave reflection method with different instruments and equipment (tunnel geological prediction [TGP]/tunnel seismic prediction [TSP]) and different vibration modes (hammering, explosives), a comparison test was carried out in Jinping Tunnel. The test results showed that the time-consumption of the hammering source was short, which can greatly reduce the impact on the construction site; different vibration sources methods of seismic wave reflection can predict the unfavorable geological sections accurately.
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Wang, Hang, Xingye Liu, and Yangkang Chen. "Separation and imaging of seismic diffractions using a localized rank-reduction method with adaptively selected ranks." GEOPHYSICS 85, no. 6 (November 1, 2020): V497—V506. http://dx.doi.org/10.1190/geo2020-0215.1.
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Seismic diffractions are weak seismic events hidden within the more dominant reflection events in a seismic profile. Separating diffraction energy from the poststack seismic profiles can help infer the subsurface discontinuities that generate the diffraction events. The separated seismic diffractions can be migrated with a traditional seismic imaging method or a specifically designed migration method to highlight the diffractors, that is, the diffraction image. Traditional diffraction separation methods based on the underlying plane-wave assumption are limited by either the inaccurate slope estimation or the plane-wave assumption of the plane-wave destruction filter and thus will cause reflection leakage into the separated diffraction profile. The leaked reflection energy will deteriorate the resolution of the subsequent diffraction imaging result. We have adopted a new diffraction separation method based on a localized rank-reduction (LRR) method. The LRR method assumes the reflection events to be locally low-rank and the diffraction energy can be separated by a rank-reduction operation. Compared to the global rank-reduction method, the LRR method is more constrained in selecting the rank and is free of separation artifacts. We use a carefully designed synthetic example to demonstrate that the LRR method can help separate the diffraction energy from a poststack seismic profile with kinematically and dynamically accurate performance.
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Tygel, M., J. Schleicher, P. Hubral, and C. Hanitzsch. "Multiple weights in diffraction stack migration." GEOPHYSICS 58, no. 12 (December 1993): 1820–30. http://dx.doi.org/10.1190/1.1443397.
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Three‐dimensional (3-D) prestack diffraction‐stack migration methods (often called Kirchhoff migration/inversion) play a fundamental role in seismic imaging. In addition to estimating the location of arbitrarily curved reflectors and the angle‐dependent reflection coefficients upon them, they can also be used to provide useful kinematic and dynamic information about the specular reflection ray that connects the source and receiver via the unknown reflecting interface. This is achieved by performing a diffraction stack more than once upon the same seismic data set using identical stacking surfaces but different weights. Some of these weights can be applied simultaneously, i.e., as a weight‐vector. The approach offers the possibility of determining various useful quantities that help to compute and interpret migrated reflections. The vector‐weighted diffraction stack is principally intended to economize the amplitude‐preserving migration that normally would require a large amount of dynamic ray tracing. A simple 2-D synthetic example shows how the method works in principle.
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Shiraishi, Kazuya, Gou Fujie, Takeshi Sato, Susumu Abe, Eiichi Asakawa, and Shuichi Kodaira. "Interferometric OBS imaging for wide-angle seismic data." GEOPHYSICS 82, no. 5 (September 1, 2017): Q39—Q51. http://dx.doi.org/10.1190/geo2016-0482.1.
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Marine wide-angle seismic data obtained using air guns and ocean-bottom seismographs (OBSs) are effective for determining large-scale subseafloor seismic velocities, but they are ineffective for imaging details of shallow seismic reflection structures because of poor illumination. Surface-related multiple reflections offer the potential to enlarge the OBS data illumination area. We have developed a new seismic imaging method for OBS surveys applying seismic interferometry, a technique that uses surface-related multiples similarly to mirror imaging. Seismic interferometry can use higher order multiple reflections than mirror imaging, which mainly uses first-order multiple reflections. A salient advantage of interferometric OBS imaging over mirror imaging is that it requires only single-component data, whereas mirror imaging requires vertical geophone and hydrophone components to separate upgoing and downgoing wavefields. We applied interferometric OBS imaging to actual 175 km long wide-angle OBS data acquired in the Nankai Trough subduction zone. We obtained clear continuous reflection images in the deep and shallow parts including the seafloor from the OBS data acquired with large spacing. Deconvolution interferometry is more suitable than correlation interferometry to improve spatial resolution because of the effects of spectral division when applied to common receiver gathers. We examined the imaging result dependence on data acquisition and processing parameters considering the data quality and target depth. An air-gun-to-OBS distance of up to 50 km and a record length of 80 s were necessary for better imaging. In addition, our decimation tests confirmed that denser OBS spacing yielded better quality and higher resolution images. Understanding crosstalk effects due to the acquisition setting will be useful to optimize methods for eliminating them. Interferometric OBS imaging merged with conventional primary reflection imaging is a powerful method for revealing crustal structures.
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Konstantaki, Laura Amalia, Deyan Draganov, Timo Heimovaara, and Ranajit Ghose. "Imaging scatterers in landfills using seismic interferometry." GEOPHYSICS 78, no. 6 (November 1, 2013): EN107—EN116. http://dx.doi.org/10.1190/geo2013-0099.1.
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A significant problem with landfills is their aftercare period. A landfill is considered to be safe for the environment only after a relatively long period of time. Until it reaches such a condition, it has to be periodically treated. Not only are treatments very expensive, but they could be dangerous as well; for example, when barriers limiting the waste break. So far, there is no established technique that can predict the leachate and gas-emission potential of a landfill, especially in time-lapse monitoring. This potential depends on the channeling of fluids due to the presence of high-density waste areas and the redistribution of the channels with time. We propose to use seismic interferometry (SI) applied to active reflection seismics to help improve the image of the waste areas (scatterers) and to monitor the subsurface changes in time. Normally, application of SI to reflection recordings from active sources at the surface would result in an erroneous retrieved result, but secondary illumination of the receivers from strongly scattering subsurface, like a landfill, would remedy this problem. We conduct modeling studies to examine the possible benefits of this approach compared to using the conventional seismic reflection method. We show that the reflections retrieved from SI can be used to obtain a clearer image of the shallower scatterers. In addition, we illustrate that time-lapse monitoring using reflections retrieved by SI shows a more repeatable result than the conventional approach in case of source nonrepeatability.
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French, W. S. "Practical seismic imaging." Exploration Geophysics 20, no. 2 (1989): 11. http://dx.doi.org/10.1071/eg989011.
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Data examples clearly show that advances in seismic reflection methods over the past few years provide the interpreter with improved geologic information. The shift over the last ten years from 2-D to 3-D surveys and the shift over the past five years from processing based on surface geometry to processing based on subsurface geometry represent the principal advancements. Despite these advancements, the seismic reflection method is not mature.There exists no unified processing method to produce a 3-D geologic picture in depth directly from the data. Current processing techniques are a conglomeration of surface referenced methods (most noise suppression techniques), subsurface referenced methods (DMO, prestack migration) and in-between methods (velocity analysis). Interpreters, processors and field people must all keep abreast of the technology of our profession in order to improve our final product: greater success in both exploration and production.
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李, 可欣. "Exploration Design of Shallow Seismic Reflection Wave Method." Advances in Geosciences 13, no. 08 (2023): 789–97. http://dx.doi.org/10.12677/ag.2023.138075.
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Wang, Linfei, Zhong Wang, Huaishan Liu, Jin Zhang, Lei Xing, and Yanxin Yin. "Hydrate-Bearing Sediment Imaging of Ghost Reflection in Vertical Cable Seismic Data Using Seismic Interferometry." Geofluids 2022 (September 25, 2022): 1–7. http://dx.doi.org/10.1155/2022/3501755.
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Marine vertical cable seismic (VCS) collects seismic waves by hydrophone array vertically suspended in seawater to prospect the offshore geological structure and monitor the reservoir. Due to its irregular source-receiver geometry, the primary imaging has narrow illustration coverage. Here, we proposed a cross-correlation transformation based on ghost wave interferometry. This method can transform the ghost reflections from the vertical cable seismic profile into the virtual surface seismic primaries just like those excited by the source and recorded by marine seismic towed-streamer below sea surface. After processing these virtual primaries with conventional method, we can obtain the ghost reflection imaging section with high resolution which effectively extend the illustration footprints in the subsurface. By application of this transform, virtual primaries are generated from the first-order ghost reflections of the actual VCS data. Then, migration of these virtual primaries provides a high-resolution image of hydrate-bearing sediments.
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Naghizadeh, Mostafa, and Mauricio Sacchi. "Ground-roll attenuation using curvelet downscaling." GEOPHYSICS 83, no. 3 (May 1, 2018): V185—V195. http://dx.doi.org/10.1190/geo2017-0562.1.
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We have developed a ground-roll attenuation strategy for seismic records that adopts the curvelet transform. The curvelet transform decomposes the seismic events based on their dip and frequency content information. The curvelet panels that contain only either reflection or ground-roll energy can be used to alter the curvelet panels with mixed reflection and ground-roll energies. We build a curvelet-domain mask function from the ground-roll-free curvelet coefficients (high frequencies) and downscale it to the ground-roll-contaminated curvelet coefficients (low frequencies). The mask function is used inside a least-squares optimization scheme to preserve the seismic reflections and attenuate the ground roll. Synthetic and real seismic data examples show the application of the proposed ground-roll attenuation method.
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IKAWA, Takeshi. "Exploration of Subsurface Structures: Reflection Seismic Method and VSP (Vertical Seismic Profiling)." Zisin (Journal of the Seismological Society of Japan. 2nd ser.) 47, no. 1 (1994): 103–12. http://dx.doi.org/10.4294/zisin1948.47.1_103.
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Wapenaar, Kees. "The Marchenko method for evanescent waves." Geophysical Journal International 223, no. 2 (August 18, 2020): 1412–17. http://dx.doi.org/10.1093/gji/ggaa375.
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SUMMARY With the Marchenko method, Green’s functions in the subsurface can be retrieved from seismic reflection data at the surface. State-of-the-art Marchenko methods work well for propagating waves but break down for evanescent waves. This paper discusses a first step towards extending the Marchenko method for evanescent waves and analyses its possibilities and limitations. In theory both the downward and upward decaying components can be retrieved. The retrieval of the upward decaying component appears to be very sensitive to model errors, but the downward decaying component, including multiple reflections, can be retrieved in a reasonably stable and accurate way. The reported research opens the way to develop new Marchenko methods that can handle refracted waves in wide-angle reflection data.
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Azizah, Fitri Rizqi, Puguh Hiskiawan, and Sri Hartanto. "Time-Depth Curve Evaluation Method for Conversion Time to Depth at Penobscot Field, Nova-Scotia, Canada." Jurnal ILMU DASAR 17, no. 1 (January 24, 2017): 25. http://dx.doi.org/10.19184/jid.v17i1.2663.
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Oil and natural gas as a fossil fuel that is essential for human civilization, and included in nonrenewable energy, making this energy source is not easy for updated availability. So that it is necessary for exploration and exploitation reliable implementation. Seismic exploration becomes the method most widely applied in the oil, in particular reflection seismic exploration. Data wells (depth domain) and seismic data (time domain) of reflection seismic survey provides information wellbore within the timescale. As for the good interpretation needed information about the state of the earth and is able to accurately describe the actual situation (scale depth). Conversion time domain into the depth domain into things that need to be done in generating qualified exploration map. Method of time-depth curve to be the method most preferred by the geophysical interpreter, in addition to a fairly short turnaround times, also do not require a large budget. Through data information check-shot consisting of the well data and seismic data, which is then exchanged plotted, forming a curve time-depth curve, has been able to produce a map domain depth fairly reliable based on the validation value obtained in the range of 54 - 176m difference compared to the time domain maps previously generated.Keywords: Energy nonrenewable, survei seismik, peta domain waktu, peta domain kedalaman, time-depth curve
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Boullenger, Boris, and Deyan Draganov. "Interferometric identification of surface-related multiples." GEOPHYSICS 81, no. 6 (November 2016): Q41—Q52. http://dx.doi.org/10.1190/geo2015-0450.1.
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The theory of seismic interferometry predicts that crosscorrelations of recorded seismic responses at two receivers yield an estimate of the interreceiver seismic response. The interferometric process applied to surface-reflection data involves the summation, over sources, of crosscorrelated traces, and it allows retrieval of an estimate of the interreceiver reflection response. In particular, the crosscorrelations of the data with surface-related multiples in the data produce the retrieval of pseudophysical reflections (virtual events with the same kinematics as physical reflections in the original data). Thus, retrieved pseudophysical reflections can provide feedback information about the surface multiples. From this perspective, we have developed a data-driven interferometric method to detect and predict the arrival times of surface-related multiples in recorded reflection data using the retrieval of virtual data as diagnosis. The identification of the surface multiples is based on the estimation of source positions in the stationary-phase regions of the retrieved pseudophysical reflections, thus not necessarily requiring sources and receivers on the same grid. We have evaluated the method of interferometric identification with a two-layer acoustic example and tested it on a more complex synthetic data set. The results determined that we are able to identify the prominent surface multiples in a large range of the reflection data. Although missing near offsets proved to cause major problems in multiple-prediction schemes based on convolutions and inversions, missing near offsets does not impede our method from identifying surface multiples. Such interferometric diagnosis could be used to control the effectiveness of conventional multiple-removal schemes, such as adaptive subtraction of multiples predicted by convolution of the data.
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Wiguna, Taufan, Rahadian Rahadian, Sri Ardhyastuti, Safira Rahmah, and Tati Zera. "SEISMIC FACIES ANALYSIS ON 2D SEISMIC REFLECTION PROFILE IN BARUNA AND JAYA LINE AT NORTH EAST JAVA BASIN." Jurnal Neutrino 9, no. 1 (October 31, 2016): 15. http://dx.doi.org/10.18860/neu.v9i1.3665.
Full textAbstract:
<p class="abstrak">Two dimension (2D) seismic profile of Baruna and Jaya lines at North-East Java Basin show seismic reflector characteristics that can be used to interpret sediment thickness and continuity. Those reflector characteristics that can be applied for seismic facies analysis that represent depositional environment. This study starts from seismic data processing that using Kirchhoff Post Stack Time Migration method which is 2D seismic profile as result. Seismic reflector characterization has been done to both 2D profiles. Seismic reflector characterization was grouped as (i) individual reflection, (ii) reflection configuration, (iii) reflection termination, (iv) external form. Individual reflection characteristics show high and medium amplitude, medium and low frequency, and continuous. Configuration reflection is continuous with parallel and subparallel type. Reflection termination shows onlap, and external form shows sheet drape. Local mound appearance can be interpreted as paleo-reef. Facies seismic anlysis result for this study area is shelf.</p>
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Tsai, C. J. "A method to analyze and verify deep crustal reflections offshore Costa Rica." GEOPHYSICS 50, no. 2 (February 1985): 196–206. http://dx.doi.org/10.1190/1.1441909.
Full textAbstract:
A multichannel seismic reflection profile across the oceanic crust seaward of the Middle America Trench off the Nicoya Peninsula, Costa Rica, shows discontinuous, low‐frequency events at 6.5 to 7.0 s. These events might first be interpreted as reflections from the Moho. However, careful analysis of the seismic data suggests that these events represent three‐dimensional (3-D) scattered energy from the rough basaltic basement. Velocity analysis indicates that root‐mean‐square (rms) velocities for these deep “reflection events” are too low to emanate from the Moho. Also, the ghost separation caused by the streamer depth decreases for increasing record time, suggesting that incident angle for these “reflections” increases with time. Furthermore, these events are approximately 13 dB stronger than would be expected for a Moho reflection. Common‐depth‐point (CDP) stacking and velocity filtering were used to attenuate the scattered noise and sideswipe from the basalt. The results show a 21 dB total reduction of scattered energy. However, Moho reflections still cannot be discerned. The results suggest (1) ambient noise after processing is 20 dB below the expected Moho level and is not a factor in detection of the Moho; (2) Moho reflectivity may be smaller than 0.1 (reflectivity is calculated from assumed velocities and densities) and could be as small as 0.05 (the detection threshold); (3) the Moho may not be a discrete reflector and may therefore represent a transition zone; and (4) Moho events may be disorganized by transmission through rough basalt so the CDP stacking process is not effective.
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Mancuso, Christopher, and Mostafa Naghizadeh. "Generalized cross-dip moveout correction of crooked 2D seismic reflection surveys." GEOPHYSICS 86, no. 4 (June 18, 2021): V285—V298. http://dx.doi.org/10.1190/geo2020-0278.1.
Full textAbstract:
In hard rock settings, reflection seismic surveys are often acquired on crooked roadways. Acquisition geometry-related noise resulting from these crooked profiles obscures the final image in places where there are crossline dipping reflectors. This noise can be prevented with cross-dip moveout (CDMO) corrections. The conventional practice is to apply corrections on straight processing lines; however, this aggravates reflection duplication and stretching artifacts. We have adopted an efficient method for CDMO correction that operates on any common midpoint (CMP) binning geometry. Our method suppresses reflection duplication in high-fold CMP bins. The strike and dip of the reflectors are decomposed into two horizontal orthogonal components and input into a 3D traveltime equation. Using a synthetic model, a processing workflow was developed to locally apply these generalized CDMO corrections. This workflow was then applied to a seismic profile acquired over the Larder-Lake Cadillac Deformation Zone in the Abitibi Greenstone Belt, Canada. The final processed seismic image showed an increased coherency of reflections rendering them more compatible with the known surface geology of the study area.
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Fomel, Sergey, Evgeny Landa, and M. Turhan Taner. "Poststack velocity analysis by separation and imaging of seismic diffractions." GEOPHYSICS 72, no. 6 (November 2007): U89—U94. http://dx.doi.org/10.1190/1.2781533.
Full textAbstract:
Small geologic features manifest themselves in seismic data in the form of diffracted waves, which are fundamentally different from seismic reflections. Using two field-data examples and one synthetic example, we demonstrate the possibility of separating seismic diffractions in the data and imaging them with optimally chosen migration velocities. Our criteria for separating reflection and diffraction events are the smoothness and continuity of local event slopes that correspond to reflection events. For optimal focusing, we develop the local varimax measure. The objectives of this work are velocity analysis implemented in the poststack domain and high-resolution imaging of small-scale heterogeneities. Our examples demonstrate the effectiveness of the proposed method for high-resolution imaging of such geologic features as faults, channels, and salt boundaries.
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Jeng, Yih. "Shallow seismic investigation of a site with poor reflection quality." GEOPHYSICS 60, no. 6 (November 1995): 1715–26. http://dx.doi.org/10.1190/1.1443904.
Full textAbstract:
A shallow seismic reflection experiment was performed on a construction site to determine the feasibility of using reflection seismology to investigate the shallow structure in a weathered sand‐gravel interlayered zone that was known to be a poor transmission of high‐frequency seismic energy. Field‐recording parameters were designed to fit the limited space of the urban construction survey area. A 7 kg sledgehammer was used to generate P‐waves and SH‐waves. Single 100 Hz geophones were deployed at 1.0 m/0.5 m group intervals, and 200/100-Hz low‐cut filters were applied prior to A to D conversion to attenuate ground roll. For SH‐wave reflections, single 14 Hz geophones and a 70-Hz low‐cut filter on the seismograph were used. The dominant frequency bands ranged from 33 to 275 Hz and were centered around 110 Hz for P‐waves. Lower dominant frequency bands 20 to 160 Hz with a dominant frequency of around 85 Hz were observed on SH‐wave records. Four seismic lines, three P‐wave recordings and one SH‐wave recording, using different sets of recording parameters and an appropriate seismic‐wave generation method produced reflections from varying depth ranges and at different resolutions. The results show that the techniques employed in this experiment may resolve the structure of a site with poor reflection quality. An f-k dip filtering and deconvolution were necessary in processing the reflection data to eliminate various types of unwanted energy. The seismic interpretations in this study were verified by drilling and by a nearby excavation.
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Abdullah, Agus, and Waskito Pranowo. "Layer-steered filter for enhancing seismic reflection interpretability." Journal of Petroleum Exploration and Production Technology 10, no. 8 (September 3, 2020): 3235–39. http://dx.doi.org/10.1007/s13202-020-00994-2.
Full textAbstract:
Abstract Seismic artifacts due to random and linear noises, low fold coverage, statics, and spatial aliasing are frequently affecting uncertainties in seismic interpretation. Several conventional methods, such as median filter, have been implemented to reduce random noises. However, this method can not be utilized for the area in which rich with stratigraphic features such as clinoforms and in the area with strong dips. We implemented layer-steered filter in order to attenuate random noises in this kind of situation. Layer-steered filter has ability to attenuate random noises but still respects to local dip events; therefore, the method provides better preservation of events and stratigraphics compared to other conventional methods such as median filter and dip-steered filter.
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van der Baan, Mirko, and Anne Paul. "Recognition and reconstruction of coherent energy with application to deep seismic reflection data." GEOPHYSICS 65, no. 2 (March 2000): 656–67. http://dx.doi.org/10.1190/1.1444763.
Full textAbstract:
Reflections in deep seismic reflection data tend to be visible on only a limited number of traces in a common midpoint gather. To prevent stack degeneration, any noncoherent reflection energy has to be removed. In this paper, a standard classification technique in remote sensing is presented to enhance data quality. It consists of a recognition technique to detect and extract coherent energy in both common shot gathers and final stacks. This technique uses the statistics of a picked seismic phase to obtain the likelihood distribution of its presence. Multiplication of this likelihood distribution with the original data results in a “cleaned up” section. Application of the technique to data from a deep seismic reflection experiment enhanced the visibility of all reflectors considerably. Because the recognition technique cannot produce an estimate of “missing” data, it is extended with a reconstruction method. Two methods are proposed: application of semblance weighted local slant stacks after recognition, and direct recognition in the linear τ-p domain. In both cases, the power of the stacking process to increase the signal‐to‐noise ratio is combined with the direct selection of only specific seismic phases. The joint application of recognition and reconstruction resulted in data images which showed reflectors more clearly than application of a single technique.
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Shen, Shi’an, Siqi Chi, Wenchao Chen, Xiaokai Wang, Cheng Wang, and Binke Huang. "Texture attribute analysis based on strong background interference suppression." Interpretation 8, no. 2 (May 1, 2020): T475—T486. http://dx.doi.org/10.1190/int-2019-0101.1.
Full textAbstract:
Seismic texture attributes are closely related to seismic facies and reservoir characteristics. However, when a strong reflection interface overlying or underlying one target layer exists, their seismic response will mask the seismic response of the target layer. In this case, it is difficult to use texture attributes to identify geologic structures and reservoirs in the target layer. We have adopted a novel method to analyze texture attributes based on suppressing strong background reflection interference. First, we use the difference between the seismic response of the lateral heterogeneous reservoir and the underlying or overlying strong reflection. Second, we use morphological component analysis to separate the poststack data set into two parts: the seismic response of the target lateral heterogeneous reservoir (e.g., a channel sand body) with a small spatial distribution and the underlying or overlying strong reflection interference (e.g., the seismic response of the stable sedimentary stratum) with a wide spatial distribution. Then, we apply the texture attribute analyzing algorithm based on the voxel cooccurrence matrix to the seismic response of the target lateral heterogeneous reservoir for identifying covered structures and characterizing the reservoir. Finally, we apply the adopted method to a 2D synthetic data set and a 3D real field data set to evaluate the effectiveness of our method. The results of texture attribute analysis indicate that our method provides more detailed structural characterization and useful information.
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Shtivelman, Vladimir, Uri Frieslander, Ezra Zilberman, and Rivka Amit. "Mapping shallow faults at the Evrona playa site using high‐resolution reflection method." GEOPHYSICS 63, no. 4 (July 1998): 1257–64. http://dx.doi.org/10.1190/1.1444427.
Full textAbstract:
A shallow high‐resolution seismic reflection survey was carried out at the Evrona playa site in the southern Arava valley, Israel. The aim of the survey was to detect and map faults in the shallow subsurface (upper 100–150 m) and establish the relationship of the morphological features revealed by aerial photographs and surface geological mapping with the faults detected in the subsurface. The survey included three seismic lines shot using the P-wave technique and one SH-wave line, which overlapped one of the P-wave lines. The seismic energy source on all the lines was a sledge hammer. The acquired reflection data were of good quality and did not require special processing efforts. The seismic sections along the lines show a sequence of reflected events within the 8–150 m range. At several locations, continuity of the events is interrupted by a system of faults. These faults form flower structures apparently related to strike‐slip motions typical of the region. Comparison of the faults mapped on the seismic sections with those expressed by surface morphological features generally show good correspondence. The results of the seismic survey provide important information for the study of paleoseismicity and seismic hazards in the investigated area.
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Schmeissner, C. M., K. T. Spikes, and D. W. Steeples. "Recording seismic reflections using rigidly interconnected geophones." GEOPHYSICS 66, no. 6 (November 2001): 1838–42. http://dx.doi.org/10.1190/1.1487126.
Full textAbstract:
Ultrashallow seismic reflection surveys require dense spatial sampling during data acquisition, which increases their cost. In previous efforts to find ways to reduce these costs, we connected geophones rigidly to pieces of channel iron attached to a farm implement. This method allowed us to plant the geophones in the ground quickly and automatically. The rigidly interconnected geophones used in these earlier studies detected first‐arrival energy along with minor interfering seismic modes, but they did not detect seismic reflections. To examine further the feasibility of developing rigid geophone emplacement systems to detect seismic reflections, we experimented with four pieces of channel iron, each 2.7 m long and 10 cm wide. Each segment was equipped with 18 geophones rigidly attached to the channel iron at 15‐cm intervals, and the spikes attached to all 18 geophones were pushed into the ground simultaneously. The geophones detected both refracted and reflected energy; however, no significant signal distortion or interference attributable to the rigid coupling of the geophones to the channel iron was observed in the data. The interfering seismic modes mentioned from the previous experiments were not detected, nor was any P‐wave propagation noted within the channel iron. These results show promise for automating and reducing the cost of ultrashallow seismic reflection and refraction surveys.
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Vasudevan, Kris, and Frederick A. Cook. "Time-frequency analysis of deep crustal reflection seismic data using Wigner-Ville distributions." Canadian Journal of Earth Sciences 38, no. 7 (July 1, 2001): 1027–35. http://dx.doi.org/10.1139/e01-003.
Full textAbstract:
One important component of deep crustal reflection seismic data in the absence of drill-hole data and surface-outcrop constraints is classifying and quantifying reflectivity patterns. One approach to this component uses a recently developed data-decomposition technique, seismic skeletonization. Skeletonized coherent events and their attributes are identified and stored in a relational database, allowing easy visualization and parameterization of the reflected wavefield. Because one useful attribute, the instantaneous frequency, is difficult to derive within the current framework of skeletonization, timefrequency analysis and a new method, empirical mode skeletonization, are used to derive it. Other attributes related to timefrequency analysis that can be derived from the methods can be used for shallow and deep reflection seismic interpretation and can supplement the seismic attributes accrued from seismic skeletonization. Bright reflections observed from below the sedimentary basin in the Southern Alberta Lithosphere Transect have recently been interpreted to be caused by highly reflective sills. Timefrequency analysis of one of these reflections shows the lateral variation of energy with instantaneous frequency for any given time and the lateral variation of energy with time for any instantaneous frequency. Results from empirical mode skeletonization for the same segment of data illustrate the differences in the instantaneous frequencies among the intrinsic modes of the data. Thus, timefrequency distribution of amplitude or energy for any signal may be a good indicator of compositional differences that can vary from one location to another.
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Xue, Ya-Juan, Jun-Xing Cao, Xing-Jian Wang, and Hao-Kun Du. "Estimation of seismic quality factor in the time-frequency domain using variational mode decomposition." GEOPHYSICS 85, no. 4 (April 30, 2020): V329—V343. http://dx.doi.org/10.1190/geo2019-0404.1.
Full textAbstract:
Seismic attenuation as represented by the seismic quality factor [Formula: see text] has a substantial impact on seismic reflection data. To effectively eliminate the interference of reflection coefficients for [Formula: see text] estimation, a new method is proposed based on the stationary convolutional model of a seismic trace using variational mode decomposition (VMD). VMD is conducted on the logarithmic spectra extracted from the time-frequency distribution of the seismic reflection data generated from the generalized S transform. For the intrinsic mode functions after VMD, mutual information and correlation analysis are used to reconstruct the signals, which effectively eliminates the influence of the reflection coefficients. The difference between the two reconstructed logarithmic spectra within the selected frequency band produces a better linear property, and it is more suitably approximated with the linear function compared to the conventional spectral-ratio method. Least-squares fitting is finally applied for [Formula: see text] estimation. Application of this method to synthetic and real data examples demonstrates the stabilization and accuracy for [Formula: see text] estimation.
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Okaya, David A., and Craig M. Jarchow. "Extraction of deep crustal reflections from shallow Vibroseis data using extended correlation." GEOPHYSICS 54, no. 5 (May 1989): 555–62. http://dx.doi.org/10.1190/1.1442682.
Full textAbstract:
Lower crustal seismic reflections can be extracted from shallow crustal seismic profiles through the application of extended correlation to uncorrelated Vibroseis seismic data. “Fixed‐bandwidth” extended correlation shortens the correlation operator before crosscorrelation, producing reflections over an increased correlation time range, all with lowered bandwidth. “Self‐truncating” extended correlation preserves the full bandwidth in the original seismic reflection times but loses bandwidth in a predictable manner at the additional (later) arrival times. Correlation wavelet shape and extra correlation time are directly related and can be calculated for specific acquisition parameters. Pre‐correlation tapering is necessary to avoid undue wavelet distortion at extended correlation times. Seismic data collected in the Basin and Range province illustrate the application of the method; the results are verified with conventional correlations of long sweep records and with impulsive source data.
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Wang, Chien‐Ying. "Detection of a recent earthquake fault by the shallow reflection seismic method." GEOPHYSICS 67, no. 5 (September 2002): 1465–73. http://dx.doi.org/10.1190/1.1512791.
Full textAbstract:
The 1999 Chi‐Chi earthquake in Taiwan was a relatively unique seismic event which activated the Chelungpu thrust fault with extraordinarily large surface ruptures up to 9.8 m horizontally and 5.6 m vertically. The fault is 80 km long, lying mostly in a north–south direction and with a reverse thrust dipping shallowly to the east. For this paper we used the shallow reflection seismic method (a small‐scale method) to map this active fault (a large‐scale structure) and provide evidence in support of the thin‐skinned thrust model for this earthquake fault. The investigation is comprised of two parts. The first concentrates on the northern portion of the fault where the fault trace was bent 70° to the northeast and was accompanied by abnormally large ground displacements and damage. The seismic sections obtained are of good quality and can be used to explore the detailed faulting mechanism. The second part aims to find the gross features of the 60 × 20‐km fault surface using limited shallow seismic measurements (about 50 seismic lines), incorporating the thin‐skinned thrust concept. This is a test to examine the feasibility of using a small‐scale economical method to study a big structure. The results are quite plausible.
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Poletto, Flavio, and Biancamaria Farina. "Synthesis and composition of virtual-reflector (VR) signals." GEOPHYSICS 75, no. 4 (July 2010): SA45—SA59. http://dx.doi.org/10.1190/1.3433311.
Full textAbstract:
The virtual-reflector (VR) method creates new seismic signals by processing seismic traces that have been produced by impulsive or transient sources. Under proper recording-coverage conditions, this technique allows a seismogram to be obtained as if there were an ideal reflector at the position of the receivers (or sources). Only the reflected signals from this reflector are synthesized. The algorithm is independent of the medium-velocity model and is based on convolution of the recorded traces and on subsequent integration of the crossconvolved signals in the receiver (or source) space. We use the VR method in combination with seismic interferometry (SI) by crosscorrelation to compose corresponding virtual-reflection events in seismic exploration. For that purpose, we use weighted-summation and data-crossfiltering approaches. In applying these combination methods, we assume common travel paths in the virtual signals, taking into account that VR and SI by crosscorrelation imply different stationary-phase conditions. We present applications in which we combine the SI-by-crosscorrelation and VR signals to (1) suppress unwanted effects, such as marine water-layer reflections in synthetic ocean-bottom-cable data, and (2) obtain virtual two-way traveltime seismograms with real borehole data from walkaway vertical seismic profiling (VSP). Analysis shows that time gating and selection of reflection events are critical steps in processing water-layer multiples.
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Zhang, Xin, and Andrew Curtis. "Bayesian full-waveform inversion with realistic priors." GEOPHYSICS 86, no. 5 (August 30, 2021): A45—A49. http://dx.doi.org/10.1190/geo2021-0118.1.
Full textAbstract:
Seismic full-waveform inversion (FWI) uses full seismic records to estimate the subsurface velocity structure. This requires a highly nonlinear and nonunique inverse problem to be solved; therefore, Bayesian methods have been used to quantify uncertainties in the solution. Variational Bayesian inference uses optimization to efficiently provide solutions. However, previously the method has only been applied to a transmission FWI problem and with strong prior information imposed on the velocity such as is never available in practice. We have found that the method works well in a seismic reflection setting and with realistically weak prior information, representing the type of problem that occurs in reality. We conclude that the method can produce high-resolution images and reliable uncertainties using data from standard reflection seismic acquisition geometry, realistic nonlinearity, and practically achievable prior information.
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Liu, Yu, and Guofeng Liu. "Three-Dimensional Processing of Reflections for Passive-Source Seismology Based on Geometric Design." Applied Sciences 13, no. 10 (May 17, 2023): 6126. http://dx.doi.org/10.3390/app13106126.
Full textAbstract:
Passive-source exploration is a method of seismic exploration that has loose requirements on the conditions of the surface, is cheap, and does not require excitation by an active source. The ambient seismic signals collected from the field over an extended period of time can be used to generate virtual-shot seismic records similar to those obtained from the seismic exploration of an active source based on the relevant correlations, and this can in turn yield information on the underground structure through a series of conventional methods of processing seismic data. Three-dimensional (3D) processing can mitigate the influence of the azimuth of random noise to yield a more representative underground structure, but requires intensive computation. In this paper, we propose a 3D method to compute reflections of a passive source based on the geometry of seismic exploration. Assuming a high quality of imaging, we use information on the predesigned geometry to choose and correlate noisy synthetic data on the reflections by a seismic body to create virtual shot data, and subsequently capture images of the 3D data on passive reflection. The use of the predesigned geometry ensures that only the important and useful parts of the dataset are used for correlation and imaging, where this reduces the cost of computation. The proposed method can thus efficiently generate high-quality 3D synthetic data.
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Sanchis, Charlotte, and Alfred Hanssen. "Enhanced local correlation stacking method." GEOPHYSICS 76, no. 3 (May 2011): V33—V45. http://dx.doi.org/10.1190/1.3552687.
Full textAbstract:
Stacking is a common technique to improve the signal-to-noise ratio (S/N) and the imaging quality of seismic data. Conventional stacking that averages equally a collection of normal moveout corrected or migrated shot gathers with a common reflection point is not always satisfactory. Instead, we propose a novel time-dependent weighted average stacking method that utilizes local correlation between each individual trace and a chosen reference trace as a measure of weight and a new weight normalization scheme that ensures meaningful amplitudes of the output. Three different reference traces have been proposed. These are based on conventional stacking, S/N estimation, and Kalman filtering. The outputs of the enhanced stacking methods, as well as their reference traces, were compared on both synthetic data and real marine migrated subsalt data. We conclude that both S/N estimation and Kalman reference stacking methods as well as the output of the enhanced stacking method yield consistently better results than conventional stacking. They exhibit cleaner and better defined reflection events and a larger number of reflections. We found that the Kalman reference method produces the best overall seismic image contrast and reveals many more reflected events, but at the cost of a higher noise level and a longer processing time. Thus, enhanced stacking using S/N estimation as reference method is a possible alternative that has the advantages of running faster, but also emphasizes some reflected events under the subsalt structure.
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Heinonen, Suvi, Marcello Imaña, David B. Snyder, Ilmo T. Kukkonen, and Pekka J. Heikkinen. "Seismic reflection profiling of the Pyhäsalmi VHMS-deposit: A complementary approach to the deep base metal exploration in Finland." GEOPHYSICS 77, no. 5 (September 1, 2012): WC15—WC23. http://dx.doi.org/10.1190/geo2011-0240.1.
Full textAbstract:
In the Pyhäsalmi case study, the seismic data is used in direct targeting of shallowly dipping mineralized zones in a massive sulfide ore system that was deformed in complex fold interference structures under high-grade metamorphic conditions. The Pyhäsalmi volcanic-hosted massive sulfide (VHMS) deposit ([Formula: see text]) is located in a Proterozoic volcanic belt in central Finland. Acoustic impedance of Pyhäsalmi ore ([Formula: see text]) is distinct from the host rocks ([Formula: see text]), enabling its detection with seismic reflection methods. Drill-hole logging further indicates that the seismic imaging of a contact zone between mafic and felsic volcanic rocks possibly hosting additional mineralizations is plausible. Six seismic profiles showed discontinuous reflectors and complicated reflectivity patterns due to the complex geology. The most prominent reflective package at 1–2 km depth was produced by shallowly dipping contacts between interlayered felsic and mafic volcanic rocks. The topmost of these bright reflections coincides with high-grade zinc mineralization. Large acoustic impedances associated with the sulfide minerals locally enhanced the reflectivity of this topmost contact zone which could be mapped over a wide area using the seismic data. Seismic data enables extrapolation of the geologic model to where no drill-hole data exists; thus, seismic reflection profiling is an important method for defining new areas of interest for deep exploration.
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Gochioco, Lawrence M. "Shallow VSP work in the U.S. Appalachian coal basin." GEOPHYSICS 63, no. 3 (May 1998): 795–99. http://dx.doi.org/10.1190/1.1444390.
Full textAbstract:
Most geophysical applications in North American coal exploration have centered around the conventional surface seismic reflection method to provide continuous subsurface coverage for evaluating both good and anomalous coal reserve areas (Ruskey, 1981; Dobecki and Bartel, 1982; Greaves, 1984; Lawton, 1985; Lyatsky and Lawton, 1988; Gochioco and Cotten, 1989; Lawton and Lyatsky, 1989; Gochioco and Kelly, 1990; Gochioco, 1991; Henson and Sexton, 1991). The surface seismic reflection method, however, has inherent resolution limitations because the seismic wavelet must propagate substantial distances through the weathered layer, resulting in rapid attenuation of the desired higher frequencies. Since the depths and thicknesses of coal seams are usually known before‐hand, it is imperative that the seismic reflection associated with the target coal seam is absolutely identified in the seismic section to avoid misinterpretations. However, it is common that checkshot data and sonic and density logs are not available to generate synthetic seismograms to assist in the interpretation of coal seismic data. To overcome some of these limitations, the vertical seismic profiling (VSP) technique was tested in a coal exploration program to provide additional information for correlation with surface seismic reflection [or common‐depth‐point (CDP)] data and a synthetic seismogram generated from density and sonic logs.
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Denelle, E. "TO TACKLE THE DECONVOLUTION PROBLEM — A POWERFUL METHOD BASED ON MORE GEOLOGICAL HYPOTHESES." APPEA Journal 26, no. 1 (1986): 192. http://dx.doi.org/10.1071/aj85019.
Full textAbstract:
The new rules of the game in hydrocarbon exploration demand an exact positioning of the seismic markers in order to define the geometry of the targets more than ever before. However, the degree of success will depend to a great extent on how accurately the amplitude of reflection coefficients can be estimated.These new requirements mean that all stages of traditional seismic processing have to be critically evaluated. It can be seen, in particular, when assessing existing deconvolution methods for seismic processing, that they are often ill-conditioned to problems posed by the targets of stratigraphic exploration or by reservoir seismic prospecting. The amplitude of the reflectivity function is often estimated inaccurately.The approach described in this paper abandons the usual hypothesis (white reflectivity spectra) made by deconvolution methods and employs as alternative information the lateral redundancies which are always present on a seismic section. Our method first estimates the location of high amplitude reflectors with good lateral continuity, by means of an elegant automatic picking program. Based on these locations, a generalized inversion can be used to yield the wavelet emitted by the source, and the amplitude of the main reflection coefficients simultaneously for each trace. All the reflection coefficients are then estimated using the amplitudes and the wavelets computed previously.The various stages of this method which is called Deconvolution-Inversion, developed by Total Compagnie Française des Pétroles, are illustrated in the paper by means of both synthetic and real examples. The ability of the method to preserve the amplitudes makes it a powerful tool for stratigraphic and reservoir seismic prospecting purposes.
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Kang, Seung-Goo, and U. Geun Jang. "Frequency-Domain Reverse-Time Migration with Analytic Green’s Function for the Seismic Imaging of Shallow Water Column Structures in the Arctic Ocean." Sensors 23, no. 14 (July 23, 2023): 6622. http://dx.doi.org/10.3390/s23146622.
Full textAbstract:
Seismic oceanography can provide a two- or three-dimensional view of the water column thermocline structure at a vertical and horizontal resolution from the multi-channel seismic dataset. Several seismic imaging methods and techniques for seismic oceanography have been presented in previous research. In this study, we suggest a new formulation of the frequency-domain reverse-time migration method for seismic oceanography based on the analytic Green’s function. For imaging thermocline structures in the water column from the seismic data, our proposed seismic reverse-time migration method uses the analytic Green’s function for numerically calculating the forward- and backward-modeled wavefield rather than the wave propagation modeling in the conventional algorithm. The frequency-domain reverse-time migration with analytic Green’s function does not require significant computational memory, resources, or a multifrontal direct solver to calculate the migration seismic images as like conventional reverse-time migration. The analytic Green’s function in our reverse-time method makes it possible to provide a high-resolution seismic water column image with a meter-scale grid size, consisting of full-band frequency components for a modest cost and in a low-memory environment for computation. Our method was applied to multi-channel seismic data acquired in the Arctic Ocean and successfully constructed water column seismic images containing the oceanographic reflections caused by thermocline structures of the water mass. From the numerical test, we note that the oceanographic reflections of the migrated seismic images reflected the distribution of Arctic waters in a shallow depth and showed good correspondence with the anomalies of measured temperatures and calculated reflection coefficients from each XCDT profile. Our proposed method has been verified for field data application and accuracy of imaging performance.
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Ker, S., Y. Le Gonidec, B. Marsset, G. K. Westbrook, D. Gibert, and T. A. Minshull. "Fine-scale gas distribution in marine sediments assessed from deep-towed seismic data." Geophysical Journal International 196, no. 3 (January 4, 2014): 1466–70. http://dx.doi.org/10.1093/gji/ggt497.
Full textAbstract:
Abstract In the context of seismic imaging of gas/gas-hydrate systems, the fine-scale structure of subseabed gas-related reflections is assessed by taking advantage of the source signature of the deep-towed high-resolution SYSIF seismic device. We demonstrate the value of an original wavelet-based method and associated multiscale seismic attributes, applied to seismic data recently acquired on the western margin of the Arctic archipelago of Svalbard. From analysis in the wavelet domain, we recognize two types of gas-related reflections associated with submetre-scale distribution of gas. We identify a thin gas-charged layer associated with an apparent normal polarity reflection, and we detect gas patches associated with a reverse-polarity bright spot with frequency-dependent elastic properties at small seismic wavelengths. The results provide valuable information on the scale of features through which gas migrates and resolve ambiguities in the interpretation of the seismic data.