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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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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.
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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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Todoeschuck, John P., and Oliver G. Jensen. "Joseph geology and seismic deconvolution." GEOPHYSICS 53, no. 11 (November 1988): 1410–14. http://dx.doi.org/10.1190/1.1442420.
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Common practice in seismic deconvolution is to assume that the reflection sequence is uncorrelated, that is, that the sequence has a white power spectrum and a delta function autocorrelation. A white spectrum implies that the acoustic impedance function has a power spectrum proportional to [Formula: see text], which is characteristic of a nonstationary Brownian process (f is frequency). However, the maximum power spectrum permissible for the acoustic impedance function is 1/f; we call a spectrum of this kind a Joseph spectrum. A Joseph spectrum corresponds to a reflection sequence with a power spectrum proportional to f and a negative autocorrelation at small lags. Joseph spectrum behavior for reflection sequences has been seen before and we show it again in a well off Newfoundland and in two wells from Quebec. If the power spectrum is proportional to f, then the first term of the discretized autocorrelation function is −0.405 of the zero‐lag term and higher terms are negligible. We construct a Joseph filter analogous to the prediction error filter (PEF) using this extra term. The method requires one additional term in the normal equations, equations which are solved iteratively. When used to deconvolve artificial seismograms from the wells, the Joseph filter recovered the reflection sequences with as little as one‐tenth the error of the PEF.
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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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Astawa, Nyoman, and Wayan Lugra. "GEOLOGI BAWAH PERMUKAAN DASAR LAUT BERDASARKAN PENAFSIRAN REKAMAN SEISMIK PANTUL DANGKAL SALURAN TUNGGAL DI PERAIRAN SELAT SUNDA." JURNAL GEOLOGI KELAUTAN 12, no. 2 (February 16, 2016): 103. http://dx.doi.org/10.32693/jgk.12.2.2014.250.
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Penelitian ini bertujuan untuk mengetahui kondisi geologi bawah permukaan dasar laut dengan metode seismik pantul dangkal saluran tunggal, dan pemeruman. Seismik stratigrafi daerah penelitian dapat dibedakan menjadi 3 (tiga) unit, yaitu Unit 1 diinterpretasikan sebagai batuan intrusi, Unit 2 yang dekat dengan Pulau Jawa sebagai batuan volkanik dan yang dekat dengan Pulau Sumatera diduga sebagai Formasi Lampung, dan batuan lava andesit, serta Unit 3 diinterpretasikan sebagai sedimen Kuarter. Kedalaman permukaan dasar yang dapat direkam berkisar antara -5 hingga -125 meter dengan perubahan yang terjadi secara bergradasi dari arah pantai ke laut.
Kata kunci : Morfologi permukaan dasar laut, seismik stratigrafi, geologi bawah permukaan, Selat Sunda
The aims of study is to determine the subsurface geology condition of Sunda Strait by using single channel shallow seismic reflection, and the sounding method. Seismic stratigraphy of the study area can be divided into three (3) units, those are Unit 1, interpreted as intrusive rocks, Unit 2, which is close to Java be expected at volcanic rocks and the adjacent of Sumatera island interpreted Lampung Formation and andesitic lava rock, while Unit 3 as suspected Quaternary sediments. The sea floor depth that can be recorded ranging from -5 to -125 metres with the changes depth gradually from the shore to the sea.
Keywords : Seafloor morphology, seismic stratigraphy, subsurface geology, Sunda Strait
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Arifin, Lukman, and Tommy Naibaho. "STRUKTUR GEOLOGI DI PERAIRAN PULAU BUTON SELATAN." JURNAL GEOLOGI KELAUTAN 13, no. 3 (February 16, 2016): 143. http://dx.doi.org/10.32693/jgk.13.3.2015.269.
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Penelitian geofisika dengan metode seismik pantul dangkal dilakukan di perairan Pulau Buton bagian selatan. Tujuan dari penelitian adalah untuk mengetahui kondisi geologi di bawah permukaan dasar laut. Dari data rekaman seismik diinterpretasikan bahwa stratigrafi seismik dibagi menjadi dua runtunan yaitu runtunan A dan B. Bila disebandingkan dengan geologi daratnya maka runtunan A termasuk dalam Formasi Wapulaka yang berumur Tersier dan runtunan B termasuk Formasi Sampolakosa yang berumur Kuater. Data rekaman tersebut juga menunjukkan adanya beberapa struktur geologi seperti sesar, lipatan, dan pengangkatan. Diduga struktur geologi tersebut berkembang dengan masih aktifnya proses tektonik hingga sekarang. Implikasi aktifnya tektonik ini dapat memperkaya dan meningkatkan potensi sumberdaya alam yang ada seperti migas dan aspal. Kata kunci seismik pantul dangkal, struktur geologi, tektonik, Perairan Pulau Buton. Geophysical research with shallow reflection seismic method carried out in the waters of the southern part of Buton Island. The aim of research is to determine the geological conditions under the sea floor. Data from seismic recordings interpreted that seismic stratigraphy is divided into two sequences, that are sequence A and B. Ifthe land geology to be compared then the sequence A is Wapulaka Formation which is Tertiary age and sequence B is Sampolakosa Formation which is Kuarter age. The recording data also indicated a number of geological structures such as faults, folds, and uplift. It was alleged that the geological structure is developing with tectonic processes are still active until now. The implications of the active tectonic can enrich and enhance the existing natural resources such as oil and gas, and bitumen. Keywords: shallow seismicreflection, geology structure, tectonic, Buton Island Waters.
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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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Hao, Xue, Lin Ren, Na Li, and Zhi Cheng Huang. "Data Mining and Knowledge Discovery Based on Denoising Algorithms in Geology Exploration." Applied Mechanics and Materials 310 (February 2013): 640–43. http://dx.doi.org/10.4028/www.scientific.net/amm.310.640.
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There are mass data in geology exploration, but it is vital to find useful information or knowledge from these data. This paper is concerned with the analysis of the seismic data by the multi-channel wiener filter algorithm and the wavelet denoising method using neighboring coefficients. Known the velocity of reflection event, utilizes the resemblance of reflection signals in each seismic trace, the multi-channel wiener filter algorithm is effective in enhance reflection events and suppress the random noise. But the wavelet denoising methods don’t need any assuming conditions. The computed simulations of these two kinds of algorithms are provided to prove the availability.
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Pereira, Ângela, Rúben Nunes, Leonardo Azevedo, Luís Guerreiro, and Amílcar Soares. "Geostatistical seismic inversion for frontier exploration." Interpretation 5, no. 4 (November 30, 2017): T477—T485. http://dx.doi.org/10.1190/int-2016-0171.1.
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Numerical 3D high-resolution models of subsurface petroelastic properties are key tools for exploration and production stages. Stochastic seismic inversion techniques are often used to infer the spatial distribution of the properties of interest by integrating simultaneously seismic reflection and well-log data also allowing accessing the spatial uncertainty of the retrieved models. In frontier exploration areas, the available data set is often composed exclusively of seismic reflection data due to the lack of drilled wells and are therefore of high uncertainty. In these cases, subsurface models are usually retrieved by deterministic seismic inversion methodologies based exclusively on the existing seismic reflection data and an a priori elastic model. The resulting models are smooth representations of the real complex geology and do not allow assessing the uncertainty. To overcome these limitations, we have developed a geostatistical framework that allows inverting seismic reflection data without the need of experimental data (i.e., well-log data) within the inversion area. This iterative geostatistical seismic inversion methodology simultaneously integrates the available seismic reflection data and information from geologic analogs (nearby wells and/or analog fields) allowing retrieving acoustic impedance models. The model parameter space is perturbed by a stochastic sequential simulation methodology that handles the nonstationary probability distribution function. Convergence from iteration to iteration is ensured by a genetic algorithm driven by the trace-by-trace mismatch between real and synthetic seismic reflection data. The method was successfully applied to a frontier basin offshore southwest Europe, where no well has been drilled yet. Geologic information about the expected impedance distribution was retrieved from nearby wells and integrated within the inversion procedure. The resulting acoustic impedance models are geologically consistent with the available information and data, and the match between the inverted and the real seismic data ranges from 85% to 90% in some regions.
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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.
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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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Ghazali, Ahmad Riza, Muhammad Hafizal Mad Zahir, Muhammad Faizal Abdul Rahim, Kefeng Xin, Farah Syazana Dzulkefli, and Junxiao Li. "Reducing seismic reflector distortion beneath gas clouds in the Malay Basin using full-wavefield imaging approaches." Leading Edge 39, no. 8 (August 2020): 591a1–591a8. http://dx.doi.org/10.1190/tle39080591a1.1.
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A seismic example from the Malay Basin is presented, demonstrating improved seismic imaging beneath gas clouds using full-wavefield imaging approaches. Overall imaging concepts, synthetic examples, and field implementation strategies are discussed, and results that tie with well information are presented. Seismic imaging beneath gas clouds using the full-wavefield redatuming technique improves the image by estimating the waveform transmission operators via equivalent-medium representation of the overburden from the gas cloud reflection response for use in a form of multidimensional deconvolution of the wavefield. The other example shown uses the full-wavefield migration seismic imaging technique, which utilizes primaries and higher-order multiples as signals to improve the reflectivity estimation in imaging. The demonstrated full-wavefield imaging approach uses information carried by the gas cloud reflection response to correct seismic image distortion. Removing the internal multiple using conventional demultiple processing in the gas cloud area will also remove the valuable information of the subsurface that it carries. Such multiples must be preserved for this method to be successful. The information is translated into transmission operators that are estimated by simulating the reflection response through an effective medium of the gas cloud overburden. The effective medium is obtained via nonlinear full-waveform inversion techniques from the reflections of the gas cloud overburden area. Finally, a deconvolutional process removes the transmission operators from the gas cloud reflections and recovers the underlying reflectors. Full-wavefield imaging can reconstruct the amplitudes of the reflection response below a gas cloud overburden zone so that the complex transmission imprint on the area underneath is removed properly. The Malay Basin field case study shows that implementation of this approach can provide a reliable amplitude image of the subsurface affected by gas clouds, calibrated and verified by the well information.
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Chen, Lei, Chao Fu, Xinji Xu, and Lichao Nie. "Imaging the Geology Ahead of a Tunnel Using Seismics and Adaptive Polarization Analysis." Journal of Environmental and Engineering Geophysics 25, no. 2 (June 2020): 189–98. http://dx.doi.org/10.2113/jeeg19-063.
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The seismic method is one of the main geophysical methods that are widely used to image the geology ahead of tunnels during tunnel construction. However, owing to the complex environment and limited observation aperture in a tunnel, symmetric false results (that appear in imaging results but not in the actual environment) frequently occur in imaging results. In a symmetric false reflection, false and true reflection points are axisymmetric around the tunnel axis. Such false results frequently cause errors in the interpretation of the geological conditions ahead of a tunnel face. To overcome this problem, a seismic method that uses adaptive polarization analysis was adopted to better image geological conditions. Based on an adaptive time window, the polarization characteristics of seismic signals were analyzed to calculate the main polarization direction. The symmetric false results in imaging results were suppressed by adopting a weighting coefficient based on the angle between the main polarization direction and ray direction. Numerical simulations revealed the superiority of the method when applied to synthetic data processing. Moreover, the method was applied to a diversion tunnel. The method successfully identified the fracture zones ahead of the tunnel face, thus significantly enhancing the safety of tunnel construction.
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Gao, Dengliang. "Latest developments in seismic texture analysis for subsurface structure, facies, and reservoir characterization: A review." GEOPHYSICS 76, no. 2 (March 2011): W1—W13. http://dx.doi.org/10.1190/1.3553479.
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In exploration geology and geophysics, seismic texture is still a developing concept that has not been sufficiently known, although quite a number of different algorithms have been published in the literature. This paper provides a review of the seismic texture concepts and methodologies, focusing on latest developments in seismic amplitude texture analysis, with particular reference to the gray level co-occurrence matrix (GLCM) and the texture model regression (TMR) methods. The GLCM method evaluates spatial arrangements of amplitude samples within an analysis window using a matrix (a two-dimensional histogram) of amplitude co-occurrence. The matrix is then transformed into a suite of texture attributes, such as homogeneity, contrast, and randomness, which provide the basis for seismic facies classification. The TMR method uses a texture model as reference to discriminate among seismic features based on a linear, least-squares regression analysis between the model and the data within an analysis window. By implementing customized texture model schemes, the TMR algorithm has the flexibility to characterize subsurface geology for different purposes. A texture model with a constant phase is effective at enhancing the visibility of seismic structural fabrics, a texture model with a variable phase is helpful for visualizing seismic facies, and a texture model with variable amplitude, frequency, and size is instrumental in calibrating seismic to reservoir properties. Preliminary test case studies in the very recent past have indicated that the latest developments in seismic texture analysis have added to the existing amplitude interpretation theories and methodologies. These and future developments in seismic texture theory and methodologies will hopefully lead to a better understanding of the geologic implications of the seismic texture concept and to an improved geologic interpretation of reflection seismic amplitude.
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Hart, Bruce S. "Whither seismic stratigraphy?" Interpretation 1, no. 1 (August 1, 2013): SA3—SA20. http://dx.doi.org/10.1190/int-2013-0049.1.
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Here, I provide an historical summary of seismic stratigraphy and suggest some potential avenues for future collaborative work between sedimentary geologists and geophysicists. Stratigraphic interpretations based on reflection geometry- or shape-based approaches have been used to reconstruct depositional histories and to make qualitative and (sometimes) quantitative predictions of rock physical properties since at least the mid-1970s. This is the seismic stratigraphy that is usually practiced by geology-focused interpreters. First applied to 2D seismic data, interest in seismic stratigraphy was reinvigorated by the development of seismic geomorphology on 3D volumes. This type of reflection geometry/shape-based interpretation strategy is a fairly mature science that includes seismic sequence analysis, seismic facies analysis, reflection character analysis, and seismic geomorphology. Rock property predictions based on seismic stratigraphic interpretations usually are qualitative, and reflection geometries commonly may permit more than one interpretation. Two geophysics-based approaches, practiced for nearly the same length of time as seismic stratigraphy, have yet to gain widespread adoption by geologic interpreters even though they have much potential application. The first is the use of seismic attributes for “feature detection,” i.e., helping interpreters to identify stratigraphic bodies that are not readily detected in conventional amplitude displays. The second involves rock property (lithology, porosity, etc.) predictions from various inversion methods or seismic attribute analyses. Stratigraphers can help quality check the results and learn about relationships between depositional features and lithologic properties of interest. Stratigraphers also can contribute to a better seismic analysis by helping to define the effects of “stratigraphy” (e.g., laminations, porosity, bedding) on rock properties and seismic responses. These and other seismic-related pursuits would benefit from enhanced collaboration between sedimentary geologists and geophysicists.
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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.
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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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Nakano, O., A. Tamari, and Y. Tobe. "Seismic reflection survey by the crooked line method applied to a coalfield in a mountainous region." Exploration Geophysics 20, no. 2 (1989): 143. http://dx.doi.org/10.1071/eg989143.
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In the past, seismic reflection surveys on land in Japan have usually been carried out along straight lines irrespective of surface terrain. However in Japan, where most of the areas are covered by mountainous terrain, it may require considerable time and cost to carry out field operations by the straight line method.From August to October in 1988, a reflection seismic survey was carried out at the Sarufutsu area in Hokkaido, Japan. The area is in a mountainous region where the straight line method was very difficult to conduct. A trial of the crooked line method was introduced to the area by laying out seismic lines along roads and valleys.Four test borings with VSP and extensive field geological surveys were carried out in this area by NEDO (New Energy and Industrial Technology Development Organization) prior to 1987, and the results show that there is a north-south trending syncline in the area and that the maximum depth of the main coal seam is approximately 600 m below the surface.The data acquisition system adopted was a 48-trace IFP digital recording system with one-millisecond sample interval.The result of the survey gives a good correlation with existing geological information.It has been concluded that seismic reflection surveys by the crooked line method are applicable for coal exploration in such a mountainous terrain.
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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.
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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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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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Todoeschuck, J. P., O. G. Jensen, and S. Labonte. "Gaussian scaling noise model of seismic reflection sequences: Evidence from well logs." GEOPHYSICS 55, no. 4 (April 1990): 480–84. http://dx.doi.org/10.1190/1.1442857.
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A simple model for reflection series is desirable for two reasons: first, to have a means of generating model reflection sequences on which to test geophysical data processing techniques, specifically methods of predictive deconvolution, and second, to suggest a way of parameterizing real reflection sequences for classification and further geologic study. In this note we wish to discuss a model suggested by Hosken (1980); our discussion is founded upon the powerful ideas of self‐similarity and scaling developed by Mandelbrot (1983) and on the paucity of typical lengths in geology. Typical lengths are common in physics problems; for example, the length of an organ pipe governs the wavelengths of the notes played. When taking photographs, geologists include some manmade object to give scale to the photo. Otherwise it is very hard to tell if, say, folds are of centimeter size or form whole mountains.
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Kukkonen, I. T., S. Heinonen, P. Heikkinen, and P. Sorjonen-Ward. "Delineating ophiolite-derived host rocks of massive sulfide Cu-Co-Zn deposits with 2D high-resolution seismic reflection data in Outokumpu, Finland." GEOPHYSICS 77, no. 5 (September 1, 2012): WC213—WC222. http://dx.doi.org/10.1190/geo2012-0029.1.
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Seismic reflection data was applied to a study of the upper crustal structures in the Outokumpu mining and exploration area in eastern Finland. The Cu-Co-Zn sulfide ore deposits of the Outokumpu area are hosted by Palaeoproterozoic ophiolite-derived altered ultrabasic rocks (serpentinite, skarn rock, and quartz rock) and black schist within turbiditic mica schist. Mining in the Outokumpu area has produced a total of 36 Mt of ore from three historical and one active mine. Seismic data comprises 2D vibroseis data surveyed along a network of local roads. The seismic sections provide a comprehensive 3D view of the reflective structures. Acoustic rock properties from downhole logging and synthetic seismograms indicate that the strongly reflective packages shown in the seismic data can be identified as the host-rock environments of the deposits. Reflectors show excellent continuity along the structural grain of the ore belt, which allows correlating reflectors with surface geology, magnetic map, and drilling sections into a broad 3D model of the ore belt. Massive ores have acoustic properties that make them directly detectable with seismic reflection methods assuming the deposit size is sufficient for applied seismic wavelengths. The seismic data revealed numerous interesting high-amplitude reflectors within the interpreted host-rock suites potentially coinciding with sulfides.
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Zang, Kai, Jiuchuan Wei, Linsong Yu, Fang Wan, Zunfang Hu, and Yang Li. "Calibration Method of Petroleum Underground Horizon Based on High Precision Gravity and Magnetic Exploration." Earth Sciences Research Journal 24, no. 3 (October 12, 2020): 345–55. http://dx.doi.org/10.15446/esrj.v24n3.90315.
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Because the high-precision calibration results of the petroleum underground layer are of great significance for oil production efficiency, research on the calibration method of the petroleum underground layer based on high precision gravity and magnetic exploration is researched. The gravity magnetic model is used to retrieve the bedrock depth, and the results of the basement structure and sedimentary rock distribution of the gravity and magnetic geology in the petroleum underground horizon of the Tongbai basin are obtained. On this basis, the geological data, logging data, seismic data, and VSP data are comprehensively used, and the layered calibration method is used to calibrate the petroleum underground layer of the Tongbai basin. Considering the seismic datum and the core elevation in the area, the rock formation is divided by various logging curves. The average time difference and density of the divided rock layers are interpolated at equal depth intervals to obtain velocity sequences and density sequences at equal time intervals and finally realize time-depth conversion. When the drilling geological horizon is unified, the synthetic record of the seismic reflection layer is compared with the geological horizon to realize the horizon calibration of the seismic reflection layer. When the local stratification is not uniform, the seismic reflection layer is calibrated by tracking the seismic reflection layer, high-precision velocity analysis, and various synthetic records to verify the reliability of the geological horizon. The results show that the proposed method can accurately survey the geological conditions of the Tongbai basin. It detected 14 basement faults, and the NW-trending and NE-trending faults controlled the basin, while the north-south faults controlled the later evolution of the basin. The method can be used for the horizon calibration of inclined wells, which is suitable not only for anisotropic media but also for formations with a less lateral variation of local formation lithology. Moreover, its usage is flexible, and it can be corrected by multiple speed data.
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Tian, Xingda, Handong Huang, Jun Gao, Yaneng Luo, Jing Zeng, Gang Cui, and Tong Zhu. "Pre-Stack Seismic Data-Driven Pre-Salt Carbonate Reef Reservoirs Characterization Methods and Application." Minerals 11, no. 9 (September 7, 2021): 973. http://dx.doi.org/10.3390/min11090973.
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Carbonate reservoirs have significant reserves globally, but the substantial heterogeneity brings intractable difficulties to exploration. In the work area, the thick salt rock reduces the resolution of pre-salt seismic signals and increases the difficulty of reservoir characterization. Therefore, this paper proposes to utilize wavelet frequency decomposition technology to depict the seismic blank reflection area’s signal and improve the pre-salt signal’s resolution. The high-precision pre-stack inversion based on Bayesian theory makes full use of information from various angles and simultaneously inverts multiple elastic parameters, effectively depicting reservoirs with substantial heterogeneity. Integrating the high-precision inversion results and the Kuster-Toksöz model, a porosity prediction method is proposed. The inversion results are consistent with the drilling rock samples and well-logging porosity results. Moreover, the reef’s accumulation and growth, which conform to the geological information, proves the accuracy of the above methods. This paper also discusses the seismic reflection characteristics of reefs and the influence of different lithological reservoirs on the seismic waveform response characteristics through forward modeling, which better proves the rationality of porosity inversion results. It provides a new set of ideas for future pre-salt carbonate reef reservoirs’ prediction and characterization methods.
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Place, Joachim, Alireza Malehmir, Karin Högdahl, Christopher Juhlin, and Katarina Persson Nilsson. "Seismic characterization of the Grängesberg iron deposit and its mining-induced structures, central Sweden." Interpretation 3, no. 3 (August 1, 2015): SY41—SY56. http://dx.doi.org/10.1190/int-2014-0212.1.
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We have conducted a reflection seismic investigation over the apatite-iron deposit at Grängesberg in central Sweden. At the time of closure in 1989, the mine was operated using the sublevel caving method down to approximately a 650-m depth. This mining technique caused subsidence and generated a network of faults that propagated from excavated zones at depth up to the surface. The Grängesberg deposit is the largest iron oxide mineralization in central Sweden and is planned to be mined again in the coming years. It is therefore imperative to have a better understanding of the ore geometry and the fault network. A reconnaissance survey consisting of two seismic lines with a total length of 3.5 km was carried out to address these issues. The profiles intersect the Grängesberg deposit and open pit, as well as the major mining-induced fracture zone present in this area. A drop-hammer source mounted on a hydraulic truck was used to generate seismic signals; cabled and wireless receivers were used for the data recording. Preprocessing of the data first required the cable- and wireless-recorded data sets to be merged before stacking all data available at each shot point. Source gathers exhibit reflections from the near surface, probably generated at lithological boundaries hosting the iron mineralization and other geologic structures. Deeper reflections were also observed. The metavolcanic assemblage hosting the mineralization and the anthropogenic fault network were depicted in the stacked sections, bringing in new elements to refine the geologic model of the area. This study also illustrated the ability of reflection seismic methods to delineate mining-induced structures in hard-rock environments. Low-velocity anomalies from the open pit and adjacent structures were depicted in tomographic sections along the two lines, which showed good agreement with known geologic features and the reflection seismic results.
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Ahmadi, Omid, Christopher Juhlin, Alireza Malehmir, and Mie Munck. "High-resolution 2D seismic imaging and forward modeling of a polymetallic sulfide deposit at Garpenberg, central Sweden." GEOPHYSICS 78, no. 6 (November 1, 2013): B339—B350. http://dx.doi.org/10.1190/geo2013-0098.1.
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We acquired a high-resolution 2D seismic profile to test the capability of the seismic method in imaging a sulfide ore body at Garpenberg, central Sweden. Delineation of the geologic structures, which surround and host the ore body, is another goal of the survey. Due to the 3D geology of the structures, a cross-dip correction performed to image out-of-the-plane reflections, resulting in a clear high amplitude anomaly at a time and location to that to be expected from near the top of the ore body. Furthermore, DMO processing and migration are applied to the data, providing images of four main reflection groups. The reflections have been interpreted as corresponding to geologic rock units in the area that partly interfere with the potential ore body signal. To further investigate the seismic response of the ore body, forward modeling by ray-tracing is applied using the ore body geometry as mapped by drilling. We use two ray-tracing approaches: standard 3D ray-tracing and an exploding reflector approach. Seven representative samples from the mine area are used to determine P-wave velocities. The measurements show a considerable contrast between the ore body and host rock. By comparing the modeled and observed data, we find that the high amplitude signal in the real seismic section most likely emanates from near the top of one concentrated ore which lies inside the larger mapped ore body that has been modeled as a resource. The base of the ore body is only observed on the synthetic data whereas a signal penetration analysis suggests that the seismic signal penetrated efficiently along the entire survey line. Presence of disseminated ore and lower fold toward the northern end of the profile could be combined reasons that make imaging the base of the ore body difficult.
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Zeng, Hongliu. "What is seismic sedimentology? A tutorial." Interpretation 6, no. 2 (May 1, 2018): SD1—SD12. http://dx.doi.org/10.1190/int-2017-0145.1.
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I have developed an alternative narrative of seismic sedimentology from a geologist’s perspective. Seismic sedimentology is a high-resolution supplement for traditional, low-resolution seismic stratigraphy, reflecting the fact that seismic responds to sedimentary bodies differently at low and high resolution. Seismic stratigraphy is a model-driven method that follows the principles of field geology and the well-based study of subsurface sedimentology, and it assumes that seismic reflections can duplicate geologic correlations. Seismic sedimentology is a more data-driven approach based on the understanding of how a seismic signal responds to thin-bedded depositional elements in the context of stratigraphy, which is a function of thickness, lithology-impedance model, wavelet phase, and frequency. Seismic sedimentology is focused on mapping seismic litho-geomorphologic facies, by joint investigation of seismic lithology and seismic geomorphology. In such an investigation, seismic lithology and seismic geomorphology are complementary, making more complete use of seismic information, and they can be more powerful in determining the sedimentary environment and reservoir quality. To reduce the knowledge gap between sedimentary geologists and seismic geophysicists, sedimentologists have to learn and master geophysical principles and techniques. To begin with, a simplified four-step workflow is recommended, which can be summarized as select-adjust-decompose-blend.
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Bergman, Björn, Ari Tryggvason, and Christopher Juhlin. "High‐resolution seismic traveltime tomography incorporating static corrections applied to a till‐covered bedrock environment." GEOPHYSICS 69, no. 4 (July 2004): 1082–90. http://dx.doi.org/10.1190/1.1778250.
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A major obstacle in tomographic inversion is near‐surface velocity variations. Such shallow velocity variations need to be known and correctly accounted for to obtain images of deeper structures with high resolution and quality. Bedrock cover in many areas consists of unconsolidated sediments and glacial till. To handle the problems associated with this cover, we present a tomographic method that solves for the 3D velocity structure and receiver static corrections simultaneously. We test the method on first‐arrival picks from deep seismic reflection data acquired in the mid‐ late to 1980s in the Siljan Ring area, central Sweden. To use this data set successfully, one needs to handle a number of problems, including time‐varying, near‐surface velocities from data recorded in winter and summer, several sources and receivers within each inversion cell, varying thickness of the cover layer in each inversion cell, and complex 3D geology. Simultaneous inversion for static corrections and velocity produces a much better image than standard tomography without statics. The velocity model from the simultaneous inversion is superior to the velocity model produced using refraction statics obtained from standard reflection seismic processing prior to inversion. Best results using the simultaneous inversion are obtained when the initial top velocity layer is set to the near‐surface bedrock velocity rather than the velocity of the cover. The resulting static calculations may, in the future, be compared to refraction static corrections in standard reflection seismic processing. The preferred final model shows a good correlation with the mapped geology and the airborne magneticmap.
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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.
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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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White, Don, David Boerner, Jianjun Wu, Steve Lucas, Eberhard Berrer, Jorma Hannila, and Rick Somerville. "Mineral exploration in the Thompson nickel belt, Manitoba, Canada, using seismic and controlled‐source EM methods." GEOPHYSICS 65, no. 6 (November 2000): 1871–81. http://dx.doi.org/10.1190/1.1444871.
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Seismic reflection and electromagnetic (EM) data were acquired near Thompson, Manitoba, Canada, to map the subsurface extent of the Paleoproterozoic, nickel ore‐bearing Ospwagan Group. These data are supplemented by surface and borehole geology and by laboratory measurements of density, seismic velocity, and electrical conductivity, which indicate that Ospwagan Group rocks are generally more seismically reflective and electrically conductive than the Archean basement rocks that envelop them. The combined seismic/EM interpretation suggests that the Thompson Nappe (cored by Ospwagan Group rocks) lies blind beneath the Archean basement gneisses, to the east of the subvertical Burntwood lineament, in a series of late recumbent folds and/or southeast‐dipping reverse faults. The EM data require that the shallowest of these fold/fault structures occur within the basement gneisses or perhaps less conductive Ospwagan Group rocks. The results of this study demonstrate how seismic and deep sounding EM methods might be utilized as regional exploration tools in the Thompson nickel belt.
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Pei, Song, Xingyao Yin, Zhaoyun Zong, and Kun Li. "High-resolution fixed-point seismic inversion." Interpretation 9, no. 3 (June 30, 2021): B25—B37. http://dx.doi.org/10.1190/int-2020-0136.1.
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Resolution improvement always presents as the crucial task in geologic inversion. Band-limited characteristics of seismic data and noise make seismic inversion complicated. Specifically, geologic inversion suffers from the deficiency of low- and high-frequency components. We have developed the fixed-point seismic inversion method to alleviate these issues. The problem of solving the objective function is transformed into the problem of finding the fixed point of the objective function. Concretely, a recursive formula between seismic signal and reflection coefficient is established, which is characterized by good convergence and verified by model examples. The error between the model value and the inverted value is reduced to approximately zero after a few iterations. The model examples show that in either case, that is, the seismic traces are noise-free or with a little noise, the model value can almost be duplicated. Even if the seismic trace is accompanied by moderate noise, optimal inverted results can still be obtained with our method. The initial model constraint is further introduced into the objective function to increase the low-frequency component of the inverted results by adding prior information into the target function. The singular value decomposition method is applied to the inversion framework, thus making a high improvement of antinoise ability. Finally, the synthetic models and seismic data are investigated following our method. The inverted results obtained from the fixed-point seismic inversion are compared with those obtained from the conventional seismic inversion, and it is found that the former has a higher resolution than the latter.
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Zhu, Hongtao, Zhiwei Zeng, Hongliu Zeng, Changgui Xu, and Fan Xiao. "Use of seismic-based new rose diagram to determine the major sediment-supply direction of progradational systems." GEOPHYSICS 84, no. 3 (May 1, 2019): IM11—IM18. http://dx.doi.org/10.1190/geo2018-0133.1.
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A conventional method for identifying sediment-supply directions is to characterize the seismic progradational reflection configuration, which is based mainly on qualitative observation of numerous seismic profiles. We have developed a more quantitative and practical way to determine the major sediment-supply direction (MSSD) using a new type of rose diagram based on seismic progradational sequence angles. In accordance with similar principles of the rose diagram used in structural geology, we have developed an analytical method and a workflow for a new rose diagram of seismic-based progradational sequence angles to determine MSSD. The Bozhong sag, a subbasin of the Bohai Bay Basin with two typical progradational sequences (I and II), provides a suitable example to analyze MSSD and test the new method. Our result indicates that the MSSD of the two progradational sequences (I and II) corresponds to azimuths of 10°–20° and 340°–350°, respectively, intuitively indicating two sequences derived from different provenance-transport systems. The new rose diagram of seismic progradational angles offers a powerful and quantitative method for seismic-based sedimentary provenance and paleocurrent analysis.
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Dean, Tim, Margarita Pavlova, Matthew Grant, Martin Bayly, Denis Sweeney, Simone Re, and Claudio Strobbia. "Imaging the near surface using velocity inversions of ultra-high-density 3D seismic data." Leading Edge 40, no. 8 (August 2021): 584–89. http://dx.doi.org/10.1190/tle40080584.1.
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Within the coal industry, there is a rich history of the use of the surface seismic method, principally for exploration and employing sparse 2D lines for broad resource delineation and structural modeling. However, the acquisition of 3D seismic surveys adjacent to open-cut mines (from which the majority of coal is extracted) for superior resource definition ahead of their expansion has been explored only recently. Although the reflection results are extremely useful and enable the mapping of faults with sub-5 m throws, there is still interest in determining if the seismic data can be used to image both structures and rock properties in the near surface. In addition to mapping near-surface structures that have geotechnical implications, the ability to map the overburden properties (which can be quite heterogeneous) is desired. Before mining activities can take place, the overburden needs to be removed. The cost of the removal method employed is directly affected by the depth of the weathered layer and rock properties. In particular, hardness can vary significantly. In this paper, we demonstrate how high-density seismic data originally acquired for reflection processing can be processed to generate high-resolution velocity (both VS and VP) depth volumes, which enable the successful identification of shallow structures and the creation of highly detailed near-surface rock-property volumes.
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Harris, James B. "Application of shallow shear-wave seismic reflection methods in earthquake hazards studies." Leading Edge 29, no. 8 (August 2010): 960–63. http://dx.doi.org/10.1190/1.3480010.
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Li, Chuangjian, Jingtao Zhao, Suping Peng, Xiaoqin Cui, and Peng Lin. "Separating and imaging diffractions of seismic waves in the full-azimuth dip-angle domain." Journal of Geophysics and Engineering 17, no. 2 (December 31, 2019): 339–56. http://dx.doi.org/10.1093/jge/gxz110.
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Abstract Seismic diffractions are ideal carriers of information on small-scale, discontinuous objects and can therefore be used to detect these geologic objects. However, recognizing diffractions is difficult because specular reflection with strong energy masks the weak diffraction. In this study, we propose a diffraction separation and imaging method based on a Mahalanobis-based and phase-based attenuation function used to modify the Kirchhoff migration formula in the full-azimuth dip-angle domain. In this domain, reflections are restricted to within the first Fresnel zone and are distributed in the vicinity of the stationary point, while diffractions are located across a wide range of azimuth and dip angles. Synthetic and field data applications suggest that this new method can effectively separate and image diffractions. The results also demonstrate the efficiency of the new method in clarifying subsurface small-scale objects, which can provide finer information about these structures for seismic interpretation.
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Yang, Feilong, Dezhi Huang, Jidong Yang, Dai Yu, Hao Luo, Chi Zhao, and Chong Zhao. "Inverse Gaussian beam stacking method for imaging both primary reflections and free-surface multiples in 2D VSP." Journal of Geophysics and Engineering 17, no. 5 (July 29, 2020): 852–60. http://dx.doi.org/10.1093/jge/gxaa034.
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Abstract In vertical seismic profiling (VSP) exploration, it is difficult to produce an accurate image for large-offset reflections only using reflection waves and the image resolution is low in traditional VSP-CDP stacking as is the number of folds of reflection points. To mitigate these problems, we present an inverse Gaussian beam stacking method for imaging both primary reflections and free-surface multiples. We first compute the stacking weighted functions at each trace location by Gaussian beam forward modeling, and then apply an inverse projection for VSP data to produce common shot gathers (CRP). Since inverse Gaussian beam stacking maps the common-shot data along finite-frequency wave-paths instead of single rays as the traditional ray-based stacking method does, it enlarges the reflection-point coverage, increases stacking fold and reduces the requirement for large bin sizes. We incorporate free-surface multiples into the proposed inverse Gaussian beam stacking, which enables us to expand the horizontal imaging aperture and mitigate the low-fold problem of primary reflections in the shallow large-offset regions for VSP surveys. Numerical examples for synthetic and field data demonstrate the feasibility and adaptability of the proposed inverse Gaussian beam stacking method for VSP data.
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Lou, Yihuai, Bo Zhang, Tengfei Lin, and Danping Cao. "Seismic horizon picking by integrating reflector dip and instantaneous phase attributes." GEOPHYSICS 85, no. 2 (January 30, 2020): O37—O45. http://dx.doi.org/10.1190/geo2018-0303.1.
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Seismic horizons are the compulsory inputs for seismic stratigraphy analysis and 3D reservoir modeling. Manually interpreting horizons on thousands of vertical seismic slices of 3D seismic survey is a time-consuming task. Automatic horizon interpreting algorithms are usually based on the seismic reflector dip. However, the estimated seismic reflector dip is usually inaccurate near and across geologic features such as unconformities. We are determined to improve the quality of picked horizons using multiple seismic attributes. We assume that seismic horizons follow the reflector dip and that the same horizons should have similar instantaneous phase values. We first generate horizon patches using a reflector dip attribute, which is similar to current methods. We use seismic coherence attribute as the stop criteria for tracking the horizon within each patch. Considering the inaccuracy of reflector dip estimates at and near the discontinuous structures such as fault and unconformities, we use the seismic instantaneous phase attribute to improve the quality of the generated horizon patches. We generate horizons by merging the residual horizon patches and only outputting the best horizon in each iteration. Our method is capable of generating a horizon for each reflection within the 3D seismic survey, and the generated horizons strictly follow the seismic reflections over the whole seismic survey. Finally, each time sample of seismic traces is assigned a chronostratigraphic relative geologic time value according to the tracked horizons.
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Louie, J. N., and J. E. Vidale. "Array analysis of reflector heterogeneity." GEOPHYSICS 56, no. 4 (April 1991): 565–71. http://dx.doi.org/10.1190/1.1443074.
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In deep crustal reflection study, as in conventional exploration seismology, it is important to determine the geometry of the physical contrasts between rocks that cause reflections, to make reliable geologic interpretations. Fundamentally different reflecting structures produce similar signatures in stacked seismic sections. We have developed a method that uses prestack records to differentiate lateral structural variations from lateral reflectivity variations and laterally homogeneous structures. Full‐wave acoustic multioffset synthetics of canonical 2-D reflector configurations, analyzed by statistically enhanced slant‐stack processes, show that lateral heterogeneity such as a wavy reflector can be identified from changes in slowness across a receiver array as a function of time. Application of these methods to deep crustal reflections, recorded in the Mojave Desert of southern California, identifies laterally heterogeneous midcrustal structures and is consistent with a laterally homogeneous Moho.
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Weglein, Arthur B., Fernanda Araújo Gasparotto, Paulo M. Carvalho, and Robert H. Stolt. "An inverse‐scattering series method for attenuating multiples in seismic reflection data." GEOPHYSICS 62, no. 6 (November 1997): 1975–89. http://dx.doi.org/10.1190/1.1444298.
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We present a multidimensional multiple‐attenuation method that does not require any subsurface information for either surface or internal multiples. To derive these algorithms, we start with a scattering theory description of seismic data. We then introduce and develop several new theoretical concepts concerning the fundamental nature of and the relationship between forward and inverse scattering. These include (1) the idea that the inversion process can be viewed as a series of steps, each with a specific task; (2) the realization that the inverse‐scattering series provides an opportunity for separating out subseries with specific and useful tasks; (3) the recognition that these task‐specific subseries can have different (and more favorable) data requirements, convergence, and stability conditions than does the original complete inverse series; and, most importantly, (4) the development of the first method for physically interpreting the contribution that individual terms (and pieces of terms) in the inverse series make toward these tasks in the inversion process, which realizes the selection of task‐specific subseries. To date, two task‐specific subseries have been identified: a series for eliminating free‐surface multiples and a series for attenuating internal multiples. These series result in distinct algorithms for free‐surface and internal multiples, and neither requires a model of the subsurface reflectors that generate the multiples. The method attenuates multiples while preserving primaries at all offsets; hence, these methods are equally well suited for subsequent poststack structural mapping or prestack amplitude analysis. The method has demonstrated its usefulness and added value for free‐surface multiples when (1) the overburden has significant lateral variation, (2) reflectors are curved or dipping, (3) events are interfering, (4) multiples are difficult to identify, and (5) the geology is complex. The internal‐multiple algorithm has been tested with good results on band‐limited synthetic data; field data tests are planned. This procedure provides an approach for attenuating a significant class of heretofore inaccessible and troublesome multiples. There has been a recent rejuvenation of interest in multiple attenuation technology resulting from current exploration challenges, e.g., in deep water with a variable water bottom or in subsalt plays. These cases are representative of circumstances where 1-D assumptions are often violated and reliable detailed subsurface information is not available typically. The inverse scattering multiple attenuation methods are specifically designed to address these challenging problems. To date it is the only multidimensional multiple attenuation method that does not require 1-D assumptions, moveout differences, or ocean‐bottom or other subsurface velocity or structural information for either free‐surface or internal multiples. These algorithms require knowledge of the source signature and near‐source traces. We describe several current approaches, e.g., energy minimization and trace extrapolation, for satisfying these prerequisites in a stable and reliable manner.
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Liu, Guofeng, Xiaohong Meng, Jianhui Ni, Zhaoxi Chen, and Da Zhang. "Evaluation of the 2D reflection seismic method toward the exploration of thrust-controlled mineral deposits in southwestern Fujian Province, China." GEOPHYSICS 83, no. 4 (July 1, 2018): B209—B220. http://dx.doi.org/10.1190/geo2017-0289.1.
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The southwestern region of the Fujian Province is one of the major ore districts in China. The current model states that mineral deposition is highly controlled by thrust structure, which means that there may be concealed deposits located deep within overlapping thrust areas. Reflection seismology, which has great depth penetration and higher resolution than other geophysical methods, has great potential to delineate complex structures and give some clues to mineralization. In 2015, an experimental 2D reflection seismic survey called “Fujian 2D” was conducted in this region. Data were acquired along a 13.8 km length, with a source interval of 60 m, and 691 identical receivers with an equal spacing of 20 m were used to record data for each source. Due to topographical restrictions caused by the source environment, the mass or position of some shots was changed. Despite the restrictions, the average fold number reached 64 for a 10 km distance along the middle of the survey line. During the data processing procedure, conventional technologies involving static correction, noise elimination, deconvolution, and iterative velocity analyses were applied. After the prestack time migration failed to obtain a high-quality imaging result, rugged prestack depth migration (PSDM) was introduced that resulted in a better quality image of the subsurface structure and which included near-surface parts of the thrusts. In addition, P- and S-wave velocities and density data were determined from two borehole cores. Forward modeling and imaging found that the Permian marble hosting the mineral deposits has lower velocity than the surrounding rocks, where contacts give rise to strong reflections. The final rugged PSDM also clearly delineated the thrust bodies and magma intrusion zones. Combining this forward modeling with the known geology of the investigated site, the Fujian 2D reflection seismic experiment demonstrates great potential for unveiling the main elements controlling mineral deposition, such as tectonic structure, stratigraphic contacts, and lithology. Our experimental results demonstrate that reflection seismology has a wide range of applications for future mineral exploration at greater depths.
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Song, Ao, Bin Song, and Rongyi Qian. "Experiment of 3D Seismic Reflection Technique for Forward Probing on TBM Tunnel Face." Journal of Environmental and Engineering Geophysics 24, no. 4 (December 2019): 609–19. http://dx.doi.org/10.2113/jeeg24.4.609.
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Geophysical technologies are used to mitigate geological hazard caused by adverse geological conditions in front of a tunnel face. The prevailing method for forward probing for tunnels constructed by a tunnel boring machine (TBM) for advance prediction is based on seismic detection. Conventional tunnel seismic prediction technology uses P- and S-waves with sources fired on the tunnel wall or face and layout receivers on the tunnel wall to acquire the reflected waves. However, the results show that most of these methods have different deficiencies that are in either low detection accuracy, short detection depth, and/or multiplicity in imaging. This paper proposes a new high resolution tunnel advance prediction technology on the face based on 3D seismic wave detection. It arranges the 3D high-density source and recording geometry on the tunnel face to receive reflected P-waves for 3D imaging. By using the 3D numerical simulation, we first analyze the energy distribution and propagation characteristics of the wave field, which proves that our method is feasible. Compared with the conventional technologies, the seismic energy propagating towards the tunnel face is stronger and produces rich reflected information. The reflected wave has the advantages of bandwidth, strong energy and little interferences from surface wave, so that the seismic phases are easy to be identified. On this basis, we present the high resolution true 3D prediction technology to obtain more comprehensive and abundant azimuth information. Our approach is further validated by an application experiment in a real-world engineering project of water conveyance tunnel. The results show that the new technique has a greater detection length, higher detection accuracy and more reliable imaging results.
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Hariri Naghadeh, Diako, Christopher J. Bean, Florent Brenguier, and Patrick J. Smith. "Retrieving reflection arrivals from passive seismic data using Radon correlation." Journal of Geophysics and Engineering 18, no. 2 (March 3, 2021): 177–91. http://dx.doi.org/10.1093/jge/gxab004.
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Abstract Since explosive and impulsive seismic sources such as dynamite, air guns, gas guns or even vibroseis can have a big impact on the environment, some companies have decided to record ambient seismic noise and use it to estimate the physical properties of the subsurface. Big challenges arise when the aim is extracting body waves from recorded passive signals, especially in the presence of strong surface waves. In passive seismic signals, such body waves are usually weak in comparison to surface waves that are much more prominent. To understand the characteristics of passive signals and the effect of natural source locations, three simple synthetic models were created. To extract body waves from simulated passive signals we propose and test a Radon-correlation method. This is a time-spatial correlation of amplitudes with a train of time-shifted Dirac delta functions through different hyperbolic paths. It is tested on a two-layer horizontal model, a three-layer model that includes a dipping layer (with and without lateral heterogeneity) and also on synthetic Marmousi model data sets. Synthetic tests show that the introduced method is able to reconstruct reflection events at the correct time-offset positions that are hidden in results obtained by the general cross-correlation method. Also, a depth migrated section shows a good match between imaged horizons and the true model. It is possible to generate off-end virtual gathers by applying the method to a linear array of receivers and to construct a velocity model by semblance velocity analysis of individually extracted gathers.
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Weibull, Wiktor Waldemar, and Børge Arntsen. "Reverse-time demigration using the extended-imaging condition." GEOPHYSICS 79, no. 3 (May 1, 2014): WA97—WA105. http://dx.doi.org/10.1190/geo2013-0232.1.
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The forward and inverse process of seismic migration and demigration or remodeling has many useful applications in seismic data processing. We evaluated a method to reobtain the seismic reflection data after migration, by inverting the common image point gathers produced by reverse-time migration (RTM) with an extended-imaging condition. This provided a transformation of the results of seismic data processing in the image domain back to the data domain. To be able to reconstruct the data with high fidelity, we set up demigration as a least-squares inverse problem and we solved it iteratively using a steepest-descent method. Because we used an extended-imaging condition, the method is not dependent on an accurate estimate of the migration-velocity field, and it is able to accurately reconstruct both primaries and multiples. At the same time, because the method is based on RTM, it can accurately handle seismic reflection data acquired over complex geologic media. Numerical results showed the feasibility of the method and highlighted some of its applications on 2D synthetic and field data sets.
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Tryggvason, Ari, Cedric Schmelzbach, and Christopher Juhlin. "Traveltime tomographic inversion with simultaneous static corrections — Well worth the effort." GEOPHYSICS 74, no. 6 (November 2009): WCB25—WCB33. http://dx.doi.org/10.1190/1.3240931.
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We have developed a first-arrival traveltime inversion scheme that jointly solves for seismic velocities and source and receiver static-time terms. The static-time terms are included to compensate for varying time delays introduced by the near-surface low-velocity layer that is too thin to be resolved by tomography. Results on a real data set consisting of picked first-arrival times from a seismic-reflection 2D/3D experiment in a crystalline environment show that the tomography static-time terms are very similar in values and distribution to refraction-static corrections computed using standard refraction-statics software. When applied to 3D seismic-reflection data, tomography static-time terms produce similar or more coherent seismic-reflection images compared to the images using corrections from standard refraction-static software. Furthermore, the method provides a much more detailed model of the near-surface bedrock velocity than standard software when the static-time terms are included in the inversion. Low-velocity zones in this model correlate with other geologic and geophysical data, suggesting that our method results in a reliable model. In addition to generally being required in seismic-reflection imaging, static corrections are also necessary in traveltime tomography to obtain high-fidelity velocity images of the subsurface.
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Zhao, Jingtao, Caixia Yu, Suping Peng, and Jingjie Cao. "Least-squares imaging of diffractions by solving a hybrid L1-L2 norm minimization problem." GEOPHYSICS 86, no. 1 (January 1, 2021): S59—S72. http://dx.doi.org/10.1190/geo2019-0720.1.
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Traditional diffraction images without a specific migration kernel for promoting focusing abilities may cause confusion to seismic interpretation because diffraction images may show a finite-array response of diffracted/scattered waves. Because diffractors are discontinuous and sparsely distributed, a least-squares diffraction-imaging method is formulated by solving a hybrid L1-L2 norm minimization problem that imposes a sparsity constraint on diffraction images. It uses two different forward modeling operators for reflections and diffractions and L2 and L1 regularizations for penalizing the amplitudes of the reflection and diffraction images, respectively. A classic Kirchhoff diffraction demigration operator is implemented on an initial diffraction image model to synthesize diffracted/scattered waves. A Kirchhoff reflection demigration operator, formulated by considering the local reflection slopes and a cosine attenuation weighting function, is implemented on an initial reflection image to synthesize the reflected waves. A modified alternating direction approach of multipliers is developed for iteratively solving this minimization problem to create diffraction images and their separated diffractions. The depths and local reflection slopes of the reflection images are fixed during this iteration. To alleviate the energy leakage between diffractions and reflections, after performing the plane-wave destruction method on the conventional migration data, its estimated reflection image and residual image are provided as the initial reflection and diffraction images, respectively. Our method can remove steep-slope reflections, increase the focusing power of the diffractions, and eliminate noise. Two numerical experiments demonstrate its capability of separating and imaging small-scale discontinuities and inhomogeneities. The exposed geologic structures in the tunnel of field coal mining further illustrate this method’s potential in ascertaining hidden faults, edges, and collapsed columns. A safety warning should be definitely required if a mining working surface is advancing these hidden geologic disasters because an emergency of water bursting or gas leakage may happen.
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Li, Kun, Xing-Yao Yin, Zhao-Yun Zong, and Hai-Kun Lin. "Seismic AVO statistical inversion incorporating poroelasticity." Petroleum Science 17, no. 5 (July 30, 2020): 1237–58. http://dx.doi.org/10.1007/s12182-020-00483-5.
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Abstract Seismic amplitude variation with offset (AVO) inversion is an important approach for quantitative prediction of rock elasticity, lithology and fluid properties. With Biot–Gassmann’s poroelasticity, an improved statistical AVO inversion approach is proposed. To distinguish the influence of rock porosity and pore fluid modulus on AVO reflection coefficients, the AVO equation of reflection coefficients parameterized by porosity, rock-matrix moduli, density and fluid modulus is initially derived from Gassmann equation and critical porosity model. From the analysis of the influences of model parameters on the proposed AVO equation, rock porosity has the greatest influences, followed by rock-matrix moduli and density, and fluid modulus has the least influences among these model parameters. Furthermore, a statistical AVO stepwise inversion method is implemented to the simultaneous estimation of rock porosity, rock-matrix modulus, density and fluid modulus. Besides, the Laplace probability model and differential evolution, Markov chain Monte Carlo algorithm is utilized for the stochastic simulation within Bayesian framework. Models and field data examples demonstrate that the simultaneous optimizations of multiple Markov chains can achieve the efficient simulation of the posterior probability density distribution of model parameters, which is helpful for the uncertainty analysis of the inversion and sets a theoretical fundament for reservoir characterization and fluid discrimination.
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Hu, Yun-bing, Yan-qing Wu, and Hou-qing Kang. "Effective wave identification and interference analysis of the seismic reflection method in mines." Journal of Coal Science and Engineering (China) 15, no. 3 (June 25, 2009): 308–12. http://dx.doi.org/10.1007/s12404-009-0318-z.
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Lin, Peng, Suping Peng, Jingtao Zhao, and Xiaoqin Cui. "Diffraction separation and imaging using multichannel singular-spectrum analysis." GEOPHYSICS 85, no. 1 (January 1, 2020): V11—V24. http://dx.doi.org/10.1190/geo2019-0201.1.
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Seismic diffractions are the responses of small-scale discontinuous structures. They contain subwavelength geologic information. Thus, diffractions can be used for high-resolution imaging. The energy of diffractions is generally much weaker than that of reflections. Therefore, diffracted energy is typically masked by specular reflected energy. Diffraction/reflection separation is a crucial preprocessing step for diffraction imaging. To resolve the diffraction-separation problem, we have developed a method based on the multichannel singular-spectrum analysis (MSSA) algorithm for diffraction separation by reflection suppression. The MSSA algorithm uses the differences in the kinematic and dynamic properties between reflections and diffractions to suppress time-linear signals (reflections) and separate weaker time-nonlinear signals (diffractions) in the common-offset or poststack domain. For the time-linear signals, the magnitudes of the singular values are proportional to the energy strength of the signals. The stronger the energy of a component of the linear signals is, the larger the corresponding singular values will be. The singular values of reflections and diffractions have dissimilar spatial distributions in the singular-value spectrum because of the differences in their linear properties and energy. Only the singular values representing diffractions are selected to reconstruct seismic signals. Synthetic data and field data are used to test our method. The results reveal the good performance of the MSSA algorithm in enhancing diffractions and suppressing reflections.
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Lin, Song, Yuan Li, Denggui Luo, and Yanlin Fu. "Research on the fracture structure and activity of the Qinling Mountains thrust nappe system in western Hubei." Canadian Journal of Earth Sciences 57, no. 1 (January 2020): 1–15. http://dx.doi.org/10.1139/cjes-2018-0118.
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The Western Hubei section of the Liangyun fault is an important structural belt of the southern Qinling Mountains thrust nappe system. As the significant activity of the Liangyun fault since the Quaternary has led to high seismic risk in the surrounding area, the research on the characteristics and activity of fault structure is of great significance for deepening the construction of a seismic safety system in this area. In this study, we conducted a field geology survey combined with quartz optical stimulated luminescence dating, scanning electron microscopy dating, and thermoluminescence dating results and comprehensive application of shallow seismic reflection and high-resolution refraction) to analyze the activities of the Liangyun fault in the Quaternary period. Sediment optical stimulated luminescence dating results of samples from the breakpoint were 134.99 + 15.52 and 160.95 + 16.88 ka. Combined with the seismic profile, outcrop observation, and previous dating results, we conclude that the new era is in fault activities in the early Pleistocene to late Pleistocene (Q2–Q3). The combined application of shallow seismic reflection and high-resolution refraction method can confirm each other’s measured results, providing more parameters for the interpretation of seismic data under complex conditions and ensuring the accuracy of data interpretation at the same time. At present, the seismic experiment scheme is less used in the field of active fault detection, since its good detection effect and the application of the trial to shallow geophysical exploration has a certain application value and global scalability.
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Bugge, Aina Juell, Jan Erik Lie, Andreas K. Evensen, Espen H. Nilsen, Odd Kolbjørnsen, and Jan Inge Faleide. "Data-driven identification of stratigraphic units in 3D seismic data using hierarchical density-based clustering." GEOPHYSICS 85, no. 5 (August 17, 2020): IM15—IM26. http://dx.doi.org/10.1190/geo2019-0413.1.
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Seismic sequences are stratigraphic units of relatively conformable seismic reflections. These units are intervals of similar sedimentation conditions, governed by sediment supply and relative sea level, and they are key elements in understanding the evolution of sedimentary basins. Conventional seismic sequence analyses typically rely on human interpretation; consequently, they are time-consuming. We have developed a new data-driven method to identify first-order stratigraphic units based on the assumption that the seismic units honor a layer-cake earth model, with layers that can be discriminated by the differences in seismic reflection properties, such as amplitude, continuity, and density. To identify stratigraphic units in a seismic volume, we compute feature vectors that describe the distribution of amplitudes, texture, and two-way traveltime for small seismic subvolumes. Here, the seismic texture is described with a novel texture descriptor that quantifies a simplified 3D local binary pattern around each pixel in the seismic volume. The feature vectors are preprocessed and clustered using a hierarchical density-based cluster algorithm in which each cluster is assumed to represent one stratigraphic unit. Field examples from the Barents Sea and the North Sea demonstrate that the proposed data-driven method can identify major 3D stratigraphic units without the need for manual interpretation, labeling, or prior geologic knowledge.
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Wu, Juan, and Min Bai. "Adaptive rank-reduction method for seismic data reconstruction." Journal of Geophysics and Engineering 15, no. 4 (May 16, 2018): 1688–703. http://dx.doi.org/10.1093/jge/aabc74.
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Abstract Seismic data reconstruction plays an important role in the whole seismic data processing and imaging workflow, especially for those data that are acquired from severe field environment and are missing a large portion of the reflection signals. The rank-reduction method is considered to be a very effective method for interpolating data that are of small curvature, e.g. the post-stack data. However, when the data are more complicated, the rank-reduction method may fail to achieve acceptable performance. A useful strategy is to use local windows to process the data so that the data in each local window satisfy the plane-wave assumption of the rank-reduction method. However, the rank in each window requires a careful selection. Traditional methods select a global rank for all windows. We have proposed an automatic algorithm to select the rank in each processing window. The energy ratio between two consecutive singular values is chosen as the criterion to define the optimal rank. We apply this strategy to seismic data interpolation and use both synthetic and field data examples to demonstrate its potential in practical applications.
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Burschil, T., T. Beilecke, and C. M. Krawczyk. "Finite-difference modelling to evaluate seismic P-wave and shear-wave field data." Solid Earth 6, no. 1 (January 13, 2015): 33–47. http://dx.doi.org/10.5194/se-6-33-2015.
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Abstract. High-resolution reflection seismic methods are an established non-destructive tool for engineering tasks. In the near surface, shear-wave reflection seismic measurements usually offer a higher spatial resolution in the same effective signal frequency spectrum than P-wave data, but data quality varies more strongly. To discuss the causes of these differences, we investigated a P-wave and a SH-wave seismic reflection profile measured at the same location on the island of Föhr, Germany and applied seismic reflection processing to the field data as well as finite-difference modelling of the seismic wave field. The simulations calculated were adapted to the acquisition field geometry, comprising 2 m receiver distance (1 m for SH wave) and 4 m shot distance along the 1.5 km long P-wave and 800 m long SH-wave profiles. A Ricker wavelet and the use of absorbing frames were first-order model parameters. The petrophysical parameters to populate the structural models down to 400 m depth were taken from borehole data, VSP (vertical seismic profile) measurements and cross-plot relations. The simulation of the P-wave wave-field was based on interpretation of the P-wave depth section that included a priori information from boreholes and airborne electromagnetics. Velocities for 14 layers in the model were derived from the analysis of five nearby VSPs (vP =1600–2300 m s-1). Synthetic shot data were compared with the field data and seismic sections were created. Major features like direct wave and reflections are imaged. We reproduce the mayor reflectors in the depth section of the field data, e.g. a prominent till layer and several deep reflectors. The SH-wave model was adapted accordingly but only led to minor correlation with the field data and produced a higher signal-to-noise ratio. Therefore, we suggest to consider for future simulations additional features like intrinsic damping, thin layering, or a near-surface weathering layer. These may lead to a better understanding of key parameters determining the data quality of near-surface shear-wave seismic measurements.