Slanted-streamer Data-adaptive Deghosting with Local Plane Waves

2014 ◽  
Author(s):  
J.E. Rickett ◽  
D.J. van Manen ◽  
P. Loganathan ◽  
N. Seymour
Keyword(s):  
Plane Waves ◽  
Data Adaptive ◽  
Local Plane ◽  
Streamer Data

Multiarrival Kirchhoff beam migration

Geophysics ◽  
2011 ◽  
Vol 76 (5) ◽  
pp. WB109-WB118 ◽  
Author(s):  
Jonathan Liu ◽  
Gopal Palacharla
Keyword(s):  
Model Updating ◽  
Plane Waves ◽  
Beam Width ◽  
Velocity Model ◽  
Model Complexity ◽  
Depth Migration ◽  
Kirchhoff Migration ◽  
Optimal Beam ◽  
Local Plane ◽  
Gaussian Beam Migration

Kirchhoff-type prestack depth migration is the method most popular for outputting offset gathers for velocity-model updating because of its flexibility and efficiency. However, conventional implementations of Kirchhoff migration use only single arrivals. This limits its ability to image complex structures such as subsalt areas. We use the beam methodology to develop a multiarrival Kirchhoff beam migration. The theory and algorithm of our beam migration are analogs to Gaussian beam migration, but we focus on attaining kinematic accuracy and implementation efficiency. The input wavefield of every common offset panel is decomposed into local plane waves at beam centers on the acquisition surface by local slant stacking. Each plane wave contributes a potential single-arrival in Kirchhoff migration. In this way, our method is able to handle multiarrivals caused by model complexity and, therefore, to overcome the limitation of conventional single-arrival Kirchhoff migration. The choice of the width of the beam is critical to the implementation of beam migration. We provide a formula for optimal beam width that achieves both accuracy and efficiency when the velocity model is reasonably smooth. The resulting structural imaging in subsalt and other structurally complex areas is of better quality than that from single-arrival Kirchhoff migration.

Imaging diffractors using wave-equation migration

Geophysics ◽  
2016 ◽  
Vol 81 (6) ◽  
pp. S459-S468 ◽  
Author(s):  
Lu Liu ◽  
Etienne Vincent ◽  
Xu Ji ◽  
Fuhao Qin ◽  
Yi Luo
Keyword(s):  
Wave Equation ◽  
Field Data ◽  
Recursive Algorithm ◽  
Median Filter ◽  
Random Noise ◽  
Plane Waves ◽  
Computationally Efficient ◽  
Imaging Point ◽  
Local Plane ◽  
Dip Angle

We have developed a fast and practical wave-equation-based migration method to image subsurface diffractors. The method is composed of three steps in our implementation. First, it decomposes extrapolated receiver wavefields at every imaging point into local plane waves by a linear Radon transform; the transform is realized by a novel computationally efficient recursive algorithm. Second, the decomposed plane waves are zero lag-correlated with the incident source wavefields, where the incident angles are computed via the structure tensor approach. The resulting prestack images are binned into dip-angle gathers according to the directions of the decomposed plane waves and the calculated incident angles. Third, a windowed median filter is applied to the dip-angle gathers to suppress the focused reflection energy, and it produces the desired diffraction images. This method is tested on synthetic and field data. The results demonstrate that it is resistant to random noise, computationally efficient, and applicable to field data in practice. The results also indicate that the diffraction images are able to provide important discontinuous geologic features, such as scattering and faulting zones, and thus are helpful for seismic interpretation.

Inviscid waves on a Lamb–Oseen vortex in a rotating stratified fluid: consequences for the elliptic instability

2008 ◽  
Vol 597 ◽  
pp. 283-303 ◽  
Author(s):  
STÉPHANE LE DIZÈS
Keyword(s):  
Plane Waves ◽  
Stratified Fluid ◽  
Lagrangian Description ◽  
Small Range ◽  
Local Approach ◽  
Coriolis Parameter ◽  
Centrifugal Instability ◽  
Local Plane ◽  
Core Modes ◽  
Oseen Vortex

The inviscid waves propagating on a Lamb–Oseen vortex in a rotating medium for an unstratified fluid and for a strongly stratified fluid are analysed using numerical and asymptotic approaches. By a local Lagrangian description, we first provide the characteristics of the local plane waves (inertia–gravity waves) as well as the local growth rate associated with the centrifugal instability when the vortex is unstable. A global WKBJ approach is then used to determine the frequencies of neutral core modes and neutral ring modes. We show that these global Kelvin modes only exist in restricted domains of the parameters. The consequences of these domain limitations for the occurrence of the elliptic instability are discussed. We argue that in an unstratified fluid the elliptic instability should be active in a small range of the Coriolis parameter which could not have been predicted from a local approach. The wavenumbers of the sinuous modes of the elliptic instability are provided as a function of the Coriolis parameter for both an unstratified fluid and a strongly stratified fluid.

Seismic demigration/migration in the curvelet domain

Geophysics ◽  
2008 ◽  
Vol 73 (2) ◽  
pp. S35-S46 ◽  
Author(s):  
Hervé Chauris ◽  
Truong Nguyen
Keyword(s):  
Input Data ◽  
Plane Waves ◽  
Synthetic Data ◽  
Velocity Model ◽  
Local Velocity ◽  
Data Set ◽  
Migration Operator ◽  
Local Plane ◽  
Seismic Images

Curvelets can represent local plane waves. They efficiently decompose seismic images and possibly imaging operators. We study how curvelets are distorted after demigration followed by migration in a different velocity model. We show that for small local velocity perturbations, the demigration/migration is reduced to a simple morphing of the initial curvelet. The derivation of the expected curvature of the curvelets shows that it is easier to sparsify the demigration/migration operator than the migration operator. An application on a 2D synthetic data set, generated in a smooth heterogeneous velocity model and with a complex reflectivity, demonstrates the usefulness of curvelets to predict what a migrated image would become in a locally different velocity model without the need for remigrating the full input data set. Curvelets are thus well suited to study the sensitivity of a prestack depth-migrated image with respect to the heterogeneous velocity model used for migration.

Gaussian beam reconstruction of seismic data

Geophysics ◽  
2019 ◽  
Vol 84 (5) ◽  
pp. S373-S387 ◽  
Author(s):  
Min Bai ◽  
Juan Wu ◽  
Hua Zhang ◽  
Mi Zhang ◽  
Yangkang Chen
Keyword(s):  
Gaussian Beam ◽  
Seismic Data ◽  
Convex Sets ◽  
Plane Waves ◽  
Reconstruction Algorithm ◽  
Research Field ◽  
Practical Significance ◽  
Reconstruction Performance ◽  
Local Plane ◽  
Gaussian Beam Migration

We have developed a new Gaussian beam reconstruction algorithm using time-domain Gaussian beam (TGB) method to decompose seismic data. The TGB is characterized by a particular arrival time, location, amplitude, orientation, curvature, and extent. TGB decomposition and reconstruction of seismic data are implemented by the plane-wave decomposition (PWD) theory. First, we evaluate the construction principle of TGB, and then we develop the PWD filter to decompose seismic data into local plane waves by estimated dip fields and curvature fields of the seismic records. Next, the local plane waves in terms of TGBs are used to reconstruct seismic data through iteratively minimizing the residual error. Afterward, Gaussian beam depth migration is performed on the reconstructed data. Finally, we analyze the reconstruction results under the circumstance of seismic data with randomly missing traces. Numerical tests indicate that for data with missing traces, the Gaussian beam method obtains better reconstruction performance than the traditional projection onto convex sets method with the same number of iterations. The combination of Gaussian beam seismic data reconstruction and migration extends the research field of Gaussian beam migration, which has an important theoretical and practical significance.

Rays and local plane waves

1983 ◽  
pp. 666-691
Author(s):  
Allan W. Snyder ◽  
John D. Love
Keyword(s):  
Plane Waves ◽  
Local Plane

Ab initio band theory approach to electron energy loss near edge structures

1988 ◽  
Vol 46 ◽  
pp. 506-507
Author(s):  
Xudong Weng ◽  
O.F. Sankey ◽  
Peter Rez
Keyword(s):  
Ab Initio ◽  
Local Density ◽  
Interpolation Method ◽  
Atomic Orbital ◽  
Plane Waves ◽  
Large Set ◽  
Theory Approach ◽  
Band Theory ◽  
Atomic Orbitals ◽  
Pseudopotential Calculations

Single electron band structure techniques have been applied successfully to the interpretation of the near edge structures of metals and other materials. Among various band theories, the linear combination of atomic orbital (LCAO) method is especially simple and interpretable. The commonly used empirical LCAO method is mainly an interpolation method, where the energies and wave functions of atomic orbitals are adjusted in order to fit experimental or more accurately determined electron states. To achieve better accuracy, the size of calculation has to be expanded, for example, to include excited states and more-distant-neighboring atoms. This tends to sacrifice the simplicity and interpretability of the method.In this paper. we adopt an ab initio scheme which incorporates the conceptual advantage of the LCAO method with the accuracy of ab initio pseudopotential calculations. The so called pscudo-atomic-orbitals (PAO's), computed from a free atom within the local-density approximation and the pseudopotential approximation, are used as the basis of expansion, replacing the usually very large set of plane waves in the conventional pseudopotential method. These PAO's however, do not consist of a rigorously complete set of orthonormal states.

Propagation and Reflection of Plane Waves in a Rotating Magneto-Elastic Fibre-Reinforced Semi Space with Surface Stress

2020 ◽  
Vol 22 (4) ◽  
pp. 939-958
Author(s):  
Indrajit Roy ◽  
D. P. Acharya ◽  
Sourav Acharya
Keyword(s):  
Surface Stress ◽  
Incident Angle ◽  
Plane Waves ◽  
Three Dimensional ◽  
Elastic Fibre ◽  
Amplitude Ratios ◽  
Governing Equations ◽  
Rotation Surface ◽  
Wave Velocities ◽  
Magnetic Field Rotation

AbstractThe present paper investigates the propagation of quasi longitudinal (qLD) and quasi transverse (qTD) waves in a magneto elastic fibre-reinforced rotating semi-infinite medium. Reflections of waves from the flat boundary with surface stress have been studied in details. The governing equations have been used to obtain the polynomial characteristic equation from which qLD and qTD wave velocities are found. It is observed that both the wave velocities depend upon the incident angle. After imposing the appropriate boundary conditions including surface stress the resultant amplitude ratios for the total displacements have been obtained. Numerically simulated results have been depicted graphically by displaying two and three dimensional graphs to highlight the influence of magnetic field, rotation, surface stress and fibre-reinforcing nature of the material medium on the propagation and reflection of plane waves.

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