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Artykuły w czasopismach na temat "One-Shot inversion method"
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Zigunov, Fernando, i John Charonko. "One-Shot Omnidirectional Pressure Integration Through Matrix Inversion". Proceedings of the International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics 21 (8.07.2024): 1–14. http://dx.doi.org/10.55037/lxlaser.21st.41.
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In this work, we present a method to perform 2D and 3D omnidirectional pressure integration from velocity measurements with a single-iteration matrix inversion approach. This work builds upon our previous work, where the rotating parallel ray approach was extended to the limit of infinite rays by taking continuous projection integrals of the ray paths and recasting the problem as an iterative matrix inversion problem. This iterative matrix equation is now ``fast-forwarded'' to the ``infinity'' iteration, leading to a different matrix equation that can be solved in a single iteration, thereby presenting the same computational complexity as the Poisson equation. We observe computational speedups of $\sim10^6$ when compared to brute-force omnidirectional integration methods, enabling the treatment of grids of $\sim 10^9$ points and potentially even larger in a desktop setup at the time of publication. Further examination of the boundary conditions of our one-shot method shows that omnidirectional pressure integration implements a new type of boundary condition, which treats the boundary points as interior points to the extent that information is available.
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Weglein, Arthur B. "A direct inverse method for subsurface properties: The conceptual and practical benefit and added value in comparison with all current indirect methods, for example, amplitude-variation-with-offset and full-waveform inversion". Interpretation 5, nr 3 (31.08.2017): SL89—SL107. http://dx.doi.org/10.1190/int-2016-0198.1.
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Direct inverse methods solve the problem of interest; in addition, they communicate whether the problem of interest is the problem that we (the seismic industry) need to be interested in. When a direct solution does not result in an improved drill success rate, we know that the problem we have chosen to solve is not the right problem — because the solution is direct and cannot be the issue. On the other hand, with an indirect method, if the result is not an improved drill success rate, then the issue can be either the chosen problem, or the particular choice within the plethora of indirect solution methods, or both. The inverse scattering series (ISS) is the only direct inversion method for a multidimensional subsurface. Solving a forward problem in an inverse sense is not equivalent to a direct inverse solution. All current methods for parameter estimation, e.g., amplitude-variation-with-offset and full-waveform inversion, are solving a forward problem in an inverse sense and are indirect inversion methods. The direct ISS method for determining earth material properties defines the precise data required and the algorithms that directly output earth mechanical properties. For an elastic model of the subsurface, the required data are a matrix of multicomponent data, and a complete set of shot records, with only primaries. With indirect methods, any data can be matched: one trace, one or several shot records, one component, multicomponent, with primaries only or primaries and multiples. Added to that are the innumerable choices of cost functions, generalized inverses, and local and global search engines. Direct and indirect parameter inversion are compared. The direct ISS method has more rapid convergence and a broader region of convergence. The difference in effectiveness increases as subsurface circumstances become more realistic and complex, in particular with band-limited noisy data.
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Jones, Glyn M., i D. B. Jovanovich. "A ray inversion method for refraction analysis". GEOPHYSICS 50, nr 11 (listopad 1985): 1701–20. http://dx.doi.org/10.1190/1.1441861.
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A new technique is presented for the inversion of head‐wave traveltimes to infer near‐surface structure. Traveltimes computed along intersecting pairs of refracted rays are used to reconstruct the shape of the first refracting horizon beneath the surface and variations in refractor velocity along this boundary. The information derived can be used as the basis for further processing, such as the calculation of near‐surface static delays. One advantage of the method is that the shape of the refractor is determined independently of the refractor velocity. With multifold coverage, rapid lateral changes in refractor geometry or velocity can be mapped. Two examples of the inversion technique are presented: one uses a synthetic data set; the other is drawn from field data shot over a deep graben filled with sediment. The results obtained using the synthetic data validate the method and support the conclusions of an error analysis, in which errors in the refractor velocity determined using receivers to the left and right of the shots are of opposite sign. The true refractor velocity therefore falls between the two sets of estimates. The refraction image obtained by inversion of the set of field data is in good agreement with a constant‐velocity reflection stack and illustrates that the ray inversion method can handle large lateral changes in refractor velocity or relief.
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Liu, Bin, Senlin Yang, Yuxiao Ren, Xinji Xu, Peng Jiang i Yangkang Chen. "Deep-learning seismic full-waveform inversion for realistic structural models". GEOPHYSICS 86, nr 1 (1.01.2021): R31—R44. http://dx.doi.org/10.1190/geo2019-0435.1.
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Velocity model inversion is one of the most important tasks in seismic exploration. Full-waveform inversion (FWI) can obtain the highest resolution in traditional velocity inversion methods, but it heavily depends on initial models and is computationally expensive. In recent years, a large number of deep-learning (DL)-based velocity model inversion methods have been proposed. One critical component in those DL-based methods is a large training set containing different velocity models. We have developed a method to construct a realistic structural model for the DL network. Our compressional-wave velocity model building method for creating dense-layer/fault/salt body models can automatically construct a large number of models without much human effort, which is very meaningful for DL networks. Moreover, to improve the inversion result on these realistic structural models, instead of only using the common-shot gather, we also extract features from the common-receiver gather as well. Through a large number of realistic structural models, reasonable data acquisition methods, and appropriate network setups, a more generalized result can be obtained through our proposed inversion framework, which has been demonstrated to be effective on the independent testing data set. The results of dense-layer models, fault models, and salt body models that we compared and analyzed demonstrate the reliability of our method and also provide practical guidelines for choosing optimal inversion strategies in realistic situations.
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Zhang, Yu, Guanquan Zhang i Norman Bleistein. "Theory of true-amplitude one-way wave equations and true-amplitude common-shot migration". GEOPHYSICS 70, nr 4 (lipiec 2005): E1—E10. http://dx.doi.org/10.1190/1.1988182.
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One-way wave operators are powerful tools for forward modeling and migration. Here, we describe a recently developed true-amplitude implementation of modified one-way operators and present some numerical examples. By “true-amplitude” one-way forward modeling we mean that the solutions are dynamically correct as well as kinematically correct. That is, ray theory applied to these equations yields the upward- and downward-traveling eikonal equations of the full wave equation, and the amplitude satisfies the transport equation of the full wave equation. The solutions of these equations are used in the standard wave-equation migration imaging condition. The boundary data for the downgoing wave is also modified from the one used in the classic theory because the latter data is not consistent with a point source for the full wave equation. When the full wave-form solutions are replaced by their ray-theoretic approximations, the imaging formula reduces to the common-shot Kirchhoff inversion formula. In this sense, the migration is true amplitude as well. On the other hand, this new method retains all of the fidelity features of wave equation migration. Computer output using numerically generated data confirms the accuracy of this inversion method. However, there are practical limitations. The observed data must be a solution of the wave equation. Therefore, the data must be collected from a single common-shot experiment. Multiexperiment data, such as common-offset data, cannot be used with this method as presently formulated.
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Zhang, Yu, Sheng Xu, Norman Bleistein i Guanquan Zhang. "True-amplitude, angle-domain, common-image gathers from one-way wave-equation migrations". GEOPHYSICS 72, nr 1 (styczeń 2007): S49—S58. http://dx.doi.org/10.1190/1.2399371.
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True-amplitude wave-equation migration provides a quality migrated image of the earth’s interior. In addition, the amplitude of the output provides an estimate of the angular-dependent reflection coefficient, similar to the output of Kirchhoff inversion. Recently, true-amplitude wave-equation migration for common-shot data has been proposed to generate amplitude-reliable, shot-domain, common-image gathers in heterogeneous media. We present a method to directly produce angle-domain common-image gathers from both common-shot and shot-receiver wave-equation migration. Generating true-amplitude, shot-domain, common-image gathers requires a deconvolution-type imaging condition using the ratio of the upgoing and downgoing wavefield, each downward-projected to the image point. Producing true-amplitude, angle-domain, common-image gathers requires, instead, the product of the upgoing wavefield and the complexconjugate of the downgoing wavefield in the imaging condition. Since multiplication is a more stable computational process than division, the new methods proposed provide more stable ways of inverting seismic data. Furthermore, the resulting common-image gathers can be directly used for migrated amplitude-variation-with angle analysis and tomography-based velocity analysis. Shot-receiver wave-equation migration requires new true-amplitude, one-way wave equations with one depth variable and transverse variables for the coordinates corresponding to sources and receivers, hence, two transverse coordinates in 2D and four transverse coordinates in 3D. We propose a modified double-square-root one-way wave equation to produce true amplitude common-image angle gathers. We also demonstrate the new methods with some synthetic examples. Some numerical examples show that the new methods we propose give better amplitude performance on the migrated angle gathers.
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Dong, Wenjie, Mark Jeffrey Emanuel, Phillip Bording i Norman Bleistein. "A computer implementation of 2.5-D common‐shot inversion". GEOPHYSICS 56, nr 9 (wrzesień 1991): 1384–94. http://dx.doi.org/10.1190/1.1443158.
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The computer implementation of a two‐and‐one‐half dimensional (2.5-D) constant density prestack inversion formalism with laterally and depth‐dependent background propagation speed is a Kirchhoff‐type inversion, summing data from a line of receivers over traveltime curves in the depth‐dependent background medium with weights determined from Born/Kirchhoff inversion theory. This theory predicts that the output will be a reflector map with peak amplitudes on each reflector being in known proportion to the angularly dependent geometrical optics reflection coefficient. The 2.5-D feature provides for out‐of‐plane spreading correction consistent with the prescribed background medium. The method is applied to a synthetic data set and to a physically modeled data set generated at the Seismic Acoustic Laboratory. The graphical output demonstrates the validity of the formalism as a Kirchhoff migration. Parameter estimation for the synthetic data confirmed the theory. Parameter estimation for the experimental data was less successful, partially due to problems with amplitude control in the original experiment and partially due to the limited aperture of the common‐shot data, thereby suggesting that a common‐offset inversion might be more useful for parameter estimation.
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Vigh, Denes, i E. William Starr. "3D prestack plane-wave, full-waveform inversion". GEOPHYSICS 73, nr 5 (wrzesień 2008): VE135—VE144. http://dx.doi.org/10.1190/1.2952623.
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Prestack depth migration has been used for decades to derive velocity distributions in depth. Numerous tools and methodologies have been developed to reach this goal. Exploration in geologically more complex areas exceeds the abilities of existing methods. New data-acquisition and data-processing methods are required to answer these new challenges effectively. The recently introduced wide-azimuth data acquisition method offers better illumination and noise attenuation as well as an opportunity to more accurately determine velocities for imaging. One of the most advanced tools for depth imaging is full-waveform inversion. Prestack seismic full-waveform inversion is very challenging because of the nonlinearity and nonuniqueness of the solution. Combined with multiple iterations of forward modeling and residual wavefield back propagation, the method is computer intensive, especially for 3D projects. We studied a time-domain, plane-wave implementation of 3D waveform inversion. We found that plane-wave gathers are an attractive input to waveform inversion with dramatically reduced computer run times compared to traditional shot-gather approaches. The study was conducted on two synthetic data sets — Marmousi2 and SMAART Pluto 1.5 — and a field data set. The results showed that a velocity field can be reconstructed well using a multiscale time-domain implementation of waveform inversion. Although the time-domain solution does not take advantage of wavenumber redundancy, the method is feasible on current computer architectures for 3D surveys. The inverted velocity volume produces a quality image for exploration geologists by using numerous iterations of waveform inversion.
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Pan, Yudi, i Lingli Gao. "Random objective waveform inversion of surface waves". GEOPHYSICS 85, nr 4 (5.06.2020): EN49—EN61. http://dx.doi.org/10.1190/geo2019-0613.1.
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Full-waveform inversion (FWI) of surface waves is becoming increasingly popular among shallow-seismic methods. Due to a huge amount of data and the high nonlinearity of the objective function, FWI usually requires heavy computational costs and may converge toward a local minimum. To mitigate these problems, we have reformulated FWI under a multiobjective framework and adopted a random objective waveform inversion (ROWI) method for surface-wave characterization. Three different measure functions were used, whereas the combination of one measure function with one shot independently provided one of the [Formula: see text] objective functions ([Formula: see text] is the total number of shots). We have randomly chose and optimized one objective function at each iteration. We performed a synthetic test to compare the performance of the ROWI and conventional FWI approaches, which showed that the convergence of ROWI is faster and more robust compared with conventional FWI approaches. We also applied ROWI to a field data set acquired in Rheinstetten, Germany. ROWI successfully reconstructed the main geologic feature, a refilled trench, in the final result. The comparison between the ROWI result and a migrated ground-penetrating radar profile further proved the effectiveness of ROWI in reconstructing the near-surface S-wave velocity model. We also ran the same field example by using a poor initial model. In this case, conventional FWI failed whereas ROWI still reconstructed the subsurface model to a fairly good level, which highlighted the relatively low dependency of ROWI on the initial model.
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Behura, Jyoti, i Roel Snieder. "Virtual Real Source: Source signature estimation using seismic interferometry". GEOPHYSICS 78, nr 5 (1.09.2013): Q57—Q68. http://dx.doi.org/10.1190/geo2013-0069.1.
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Knowledge of the seismic source signature is crucial in numerousproblems in exploration seismology, especially in full-waveform inversion. However, existing methods of source signature estimation like statistical methods and well-log-based methods suffer from several drawbacks arising from assumptions such as whiteness of the reflectivity series and the minimum-phase character of the wavelet. Also, estimation of the source signature using wave-theoretical methods requires the recording of the wavefield and its normal derivative or additional recordings above the receiver surface which are not always available. We introduce a method, called the Virtual Real Source, of extracting the source signature based on the theory of seismic interferometry, also known as the virtual source method. This method is independent of the assumptions and drawbacks of the above-mentioned methods. The only requirement for the method of Virtual Real Source is to have a virtual source location coincide with the physical shot position whose source signature is desired. The virtual source location does not necessarily have to be a zero-offset receiver because one can use interpolation for it. The source signature is extracted by deconvolving the real recording at a receiver from the virtual source recording. Through modeling examples, we show that Virtual Real Source produces accurate source signatures even for complicated subsurface structures and source signatures, and is robust in the presence of noise. Source signature of every shot in a survey can be extracted reliably as long as the source signatures have similar amplitude spectra. The phase spectrum of the source signature is always extracted accurately even if it varies randomly from one shot to another. The Virtual Real Source applied on a 2D streamer data set from the North Viking Graben in the North Sea extracts all the airgun signatures with the main pulse and the bubble oscillation.
Streszczenia konferencji na temat "One-Shot inversion method"
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Kane, Daniel J., i Rick Trebino. "Single-Shot Measurement of the Intensity and Phase of a Femtosecond Pulse Using the Optical-Kerr Effect". W Nonlinear Optics. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/nlo.1992.mc6.
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We report and demonstrate the first technique for measuring the full, time-dependent intensity and phase, E(t), of an individual femtosecond pulse. This new technique, which we call “frequency-resolved optical gating” (FROG), uses the polarization-spectroscopy optical-gate arrangement with an instantaneously responding χ(3) sample medium, such as glass. Here, however, the pulse is split and one version of the pulse gates the other (see Figs. 1 and 2). We then measure the signal spectrum as a function of the delay between the two input pulses. Because the signal pulse is shorter than the input pulses (by a factor of √3 for Gaussian pulses), the signal pulse reveals, for a given delay, the frequency of a particular temporal component of the ultrashort pulse (See Fig. 2). For reasonably well-behaved pulses, the output plot of signal intensity vs. frequency and delay graphically displays the pulse instantaneous frequency vs. time (See Fig. 3). More importantly, inversion of ω(t) to obtain t(ω), followed by integration of this result, yields the phase vs. frequency, φ(ω). In conjunction with the pulse spectrum, I(ω), which is also naturally obtained in FROG, this result yields the full amplitude and phase of the pulse field in the frequency domain, E(ω). Simple Fourier transformation yields E(t). We have demonstrated the method using a microscope slide as a nonlinear medium and ~620-nm, ~200- μJ, nearly transform-limited ~100-fsec pulses and ~200-fsec chirped pulses.