Prestack multicomponent migration

Geophysics ◽  
1997 ◽  
Vol 62 (2) ◽  
pp. 598-613 ◽  
Author(s):  
Jingping Zhe ◽  
Stewart A. Greenhalgh
Keyword(s):  
Seismic Data ◽  
Numerical Test ◽  
Computer Time ◽  
Complex Structures ◽  
Test Results ◽  
S Wave ◽  
Displacement Potential ◽  
S Waves ◽  
And Function ◽  
Wavefield Extrapolation

Prestack elastic migration by displacement potential extrapolation is a mixed, systematic, and function‐blocked vector wavefield migration algorithm. A new wavefield extrapolation method for inhomogeneous media is introduced here according to the following sequence: displacements ← potentials ← extrapolation of the potentials ← displacements, which is relatively accurate and not computer‐time intensive. Traveltimes of both direct downgoing P‐ and S‐waves, which are necessary in elastic migration, are calculated with a modified convolutional acoustic forward modeling program applicable to complex structures. A new image condition based on the time consistent principle is developed. It involves first obtaining an image condition section. Then two images (P P and S S) are obtained from the product of the extrapolated and decomposed P P‐ and S S‐wave displacement amplitudes and the image condition section. All P P‐, P S‐, S P‐ and S S‐waves are considered when the image condition section is calculated. The image condition section minimizes cross‐talk between modes. Compared to previous treatments, the newly developed image condition formula is superior since it allows migration of multicomponent seismic data produced using a combined P and S source. Numerical test results are very encouraging and clearly demonstrate the robustness of the technique. Further work is continuing so as to overcome ray angle and polarity problems in the image condition.

Vector-wave-based elastic reverse time migration of ocean-bottom 4C seismic data

Geophysics ◽  
2018 ◽  
Vol 83 (4) ◽  
pp. S333-S343 ◽  
Author(s):  
Pengfei Yu ◽  
Jianhua Geng ◽  
Jiqiang Ma
Keyword(s):  
Seismic Data ◽  
Ocean Bottom ◽  
Reverse Time ◽  
Reverse Time Migration ◽  
S Wave ◽  
Vector Wave ◽  
S Waves ◽  
Time Migration ◽  
Multicomponent Seismic ◽  
Wavefield Extrapolation

The acoustic-elastic coupled equation (AECE) has several advantages when compared with conventional scalar-wave-based elastic reverse time migration (ERTM) methods used to image ocean-bottom multicomponent seismic data. In particular, vector-wave-based ERTM requires vectorial P- and S-waves on the source and receiver sides, but these cannot be directly obtained from wavefield extrapolation using AECE. Therefore, we have developed a P- and S-wave vector decomposition (VD) approach within AECE; this approach enables the deduction of a novel VD-based AECE, from which vectorial P- and S-waves can be obtained directly via wavefield extrapolation. We are also able to derive a new formulation suitable for vector-wave-based ERTM of ocean-bottom multicomponent seismic data that can generate a phase-preserved PS-image. Three synthetic examples illustrate the validity and effectiveness of our new method.

The present state of seismic data acquisition: One view

Geophysics ◽  
1985 ◽  
Vol 50 (12) ◽  
pp. 2443-2451 ◽  
Author(s):  
Stanley J. Laster
Keyword(s):  
Data Acquisition ◽  
Seismic Data ◽  
Three Dimensional ◽  
Artificial Satellites ◽  
S Wave ◽  
Positioning Systems ◽  
S Waves ◽  
Exploration And Production ◽  
Seismic Data Acquisition ◽  
Marine Applications

Seismic data acquisition in the mid‐1980s is briefly reviewed. In terms of hardware, the trend has been toward an increased number of data channels in both land and marine applications. This has led to the development of digital telemetry systems. Positioning systems, particularly for marine work, have made use of artificial satellites. The perceived need for S‐wave information has led to development of S‐wave sources such as the horizontal vibrator. S‐waves in a few cases have been used to validate hydrocarbon indicators on seismic records. There has been a distinct trend toward three‐dimensional (3-D) seismic recording, both on land and at sea, and for both exploration and production applications.

Prestack scalar reverse-time depth migration of 3D elastic seismic data

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. S199-S207 ◽  
Author(s):  
Robert Sun ◽  
George A. McMechan ◽  
Chen-Shao Lee ◽  
Jinder Chow ◽  
Chen-Hong Chen
Keyword(s):  
Wave Equation ◽  
Finite Difference ◽  
Seismic Data ◽  
P Wave ◽  
Scalar Wave ◽  
Reverse Time ◽  
S Wave ◽  
Absolute Value ◽  
S Waves ◽  
Finite Difference Solution

Using two independent, 3D scalar reverse-time depth migrations, we migrate the reflected P- and S-waves in a prestack 3D, three-component (3-C), elastic seismic data volume generated with a P-wave source in a 3D model and recorded at the top of the model. Reflected P- and S-waves are extracted by divergence (a scalar) and curl (a 3-C vector) calculations, respectively, during shallow downward extrapolation of the elastic seismic data. The imaging time for the migrations of both the reflected P- and P-S converted waves at each point is the one-way P-wave traveltime from the source to that point.The divergence (the extracted P-waves) is reverse-time extrapolated using a finite-difference solution of the 3D scalar wave equation in a 3D P-velocity modeland is imaged to obtain the migrated P-image. The curl (the extracted S-waves) is first converted into a scalar S-wavefield by taking the curl’s absolute value as the absolute value of the scalar S-wavefield and assigning a positive sign if the curl is counterclockwise relative to the source or a negative sign otherwise. This scalar S-wavefield is then reverse-time extrapolated using a finite-difference solution of the 3D scalar wave equation in a 3D S-velocity model, and it is imaged with the same one-way P-wave traveltime imaging condition as that used for the P-wave. This achieves S-wave polarity uniformity and ensures constructive S-wave interference between data from adjacent sources. The algorithm gives satisfactory results on synthetic examples for 3D laterally inhomogeneous models.

Real data results of Kirchhoff elastic wave migration

Geophysics ◽  
1986 ◽  
Vol 51 (4) ◽  
pp. 1006-1011 ◽  
Author(s):  
Ting‐Fan Dai ◽  
John T. Kuo
Keyword(s):  
Seismic Data ◽  
Real Data ◽  
Horizontal Layer ◽  
S Wave ◽  
P Waves ◽  
S Waves ◽  
Surface Data ◽  
And Migration ◽  
Wave Migration ◽  
Kirchhoff Integral

Although Kirchhoff integral migration has attracted considerable attention for seismic data processing since the early 1970s, it, like all other seismic migration methods, is only applicable to compressional (P) waves. Because of a recent surge of interest in shear (S) waves, Kuo and Dai (1984) developed the Kirchhoff elastic (P and S) wave migration (KEWM) formulation and migration principle for the case of source and receiver noncoincidence. They obtained encouraging results using two‐dimensional (2-D) synthetic surface data from various geometric elastic models, including a dipping layer, a composite dipping and horizontal layer, and two layers over a half‐space.

Seismic monitoring of fluid fronts: An experimental study

Geophysics ◽  
2002 ◽  
Vol 67 (1) ◽  
pp. 221-229 ◽  
Author(s):  
Angelika‐M. Wulff ◽  
Svein Mjaaland
Keyword(s):  
Seismic Data ◽  
Seismic Monitoring ◽  
S Wave ◽  
Velocity Amplitude ◽  
S Waves ◽  
Transmitted Waves ◽  
Porous Sandstone ◽  
Grain Surface ◽  
Local Fluid Flow ◽  
Transmission And Reflection

Seismic signatures of time‐dependent reservoir processes, necessary for the interpretation of 4‐D seismic data, are still insufficiently described. This experiment was designed to monitor fluid‐front movements and saturation changes and to identify the related seismic signatures. Ultrasonic P‐ and S‐wave transmission and reflection measurements were used to monitor the waterflooding of a porous sandstone. The sandstone was flooded in steps by filling a tank in which the room‐dry cubic (50‐cm side) block of rock was placed. Waterflooding caused the velocity, amplitude, and frequency of the transmitted waves to diminish significantly; however, the changes were reversible by drying. The maximum reduction of the velocities was 7% and 12% for P‐ and S‐waves, respectively. The velocity and amplitude behavior can be explained by the Biot‐Gassmann's theory, local fluid flow, and grain‐surface effects. The correct interpretation of seismic signatures of fluid processes in reservoirs thus involves a knowledge of rock physical relations and attenuation mechanisms. Even at small saturations, reflections from the block bottom were strongly attenuated, but those from the upgoing water front could be monitored. The latter reflections were best observed in differential seismic traces, confirming that seismic monitoring can observe moving fronts directly.

Phase correction in separating P‐ and S‐waves in elastic data

Geophysics ◽  
2001 ◽  
Vol 66 (5) ◽  
pp. 1515-1518 ◽  
Author(s):  
Robert Sun ◽  
Jinder Chow ◽  
Kuang‐Jung Chen
Keyword(s):  
Wave Equation ◽  
Velocity Model ◽  
Acoustic Wave Equation ◽  
S Wave ◽  
Elastic Wave Equation ◽  
Wave Type ◽  
P Waves ◽  
S Waves ◽  
Elastic Data ◽  
Wavefield Extrapolation

Two‐dimensional elastic data containing reflected P‐waves and converted S‐wave generated by a P‐source may be separated using dilatation and rotation calculation (Sun, 1999). The algorithm is a combination of elastic full wavefield extrapolation (Sun and McMechan, 1986; Chang and McMechan, 1987, 1994) and wave‐type separation using dilatation (divergence) and rotation (curl) calculations (Dellinger and Etgen, 1990). It includes (1) downward extrapolating the (multicomponent) elastic data in an elastic velocity model using the elastic wave equation, (2) calculating the dilatation to represent pure P‐waves and calculating the rotation to represent pure S‐waves at some depth, and (3) upward extrapolating the dilatation in a P‐velocity model and upward extrapolating the rotation in an S‐velocity model, using the acoustic wave equation for each.

scholarly journals Three-component amplitude versus offset analysis

1989 ◽  
Vol 20 (2) ◽  
pp. 257
Author(s):  
D.R. Miles ◽  
G. Gassaway ◽  
L. Bennett ◽  
R. Brown
Keyword(s):  
Seismic Data ◽  
P Wave ◽  
S Wave ◽  
Converted Wave ◽  
P Waves ◽  
S Waves ◽  
Avo Analysis ◽  
Avo Inversion ◽  
Amplitude Versus Offset ◽  
Converted Waves

Three-component (3-C) amplitude versus offset (AVO) inversion is the AVO analysis of the three major energies in the seismic data, P-waves, S-waves and converted waves. For each type of energy the reflection coefficients at the boundary are a function of the contrast across the boundary in velocity, density and Poisson's ratio, and of the angle of incidence of the incoming wave. 3-C AVO analysis exploits these relationships to analyse the AVO changes in the P, S, and converted waves. 3-C AVO analysis is generally done on P, S, and converted wave data collected from a single source on 3-C geophones. Since most seismic sources generate both P and S-waves, it follows that most 3-C seismic data may be used in 3-C AVO inversion. Processing of the P-wave, S-wave and converted wave gathers is nearly the same as for single-component P-wave gathers. In split-spread shooting, the P-wave and S-wave energy on the radial component is one polarity on the forward shot and the opposite polarity on the back shot. Therefore to use both sides of the shot, the back shot must be rotated 180 degrees before it can be stacked with the forward shot. The amplitude of the returning energy is a function of all three components, not just the vertical or radial, so all three components must be stacked for P-waves, then for S-waves, and finally for converted waves. After the gathers are processed, reflectors are picked and the amplitudes are corrected for free-surface effects, spherical divergence and the shot and geophone array geometries. Next the P and S-wave interval velocities are calculated from the P and S-wave moveouts. Then the amplitude response of the P and S-wave reflections are analysed to give Poisson's ratio. The two solutions are then compared and adjusted until they match each other and the data. Three-component AVO inversion not only yields information about the lithologies and pore-fluids at a specific location; it also provides the interpreter with good correlations between the P-waves and the S-waves, and between the P and converted waves, thus greatly expanding the value of 3-C seismic data.

Pengembangan Instrumen Penilaian Kinerja pada Praktikum Struktur dan Fungsi Sel Di SMA Negeri 1 Kota Jambi

2016 ◽  
Vol 5 (2) ◽  
Author(s):  
Nugroho Budhiwaluyo ◽  
Rayandra Asyhar ◽  
Bambang Hariyadi
Keyword(s):  
Performance Assessment ◽  
Student Performance ◽  
Cell Structure ◽  
Structure And Function ◽  
Assessment Instrument ◽  
Product Performance ◽  
Development Model ◽  
Test Results ◽  
Validity And Reliability ◽  
And Function

  This research aims to produce a final product in the form of a performance-assessment instrument on Cell Structure and Function experiment. The development model is ADDIE. Based on expert's judgment, the instrument was valid and can be tested in the field. Field-test results shown that the product performs high validity and reliability value on measuring student performance on Cell Structure and Function experiment. Therefore, it is concluded that this performance-assessment instrument theoretically and practically has a good quality for measuring student performance in both process and product performance on Cell Structure and Function experiment. Keywords: Development, Performance-Assessment Instrument, Cell Structure and Function Experiment 

scholarly journals Responses of dipole-source reflected shear waves in acoustically slow formations

2019 ◽  
Author(s):  
Hao Wang ◽  
Ning Li ◽  
Caizhi Wang ◽  
Hongliang Wu ◽  
Peng Liu ◽  
...  
Keyword(s):  
Finite Difference Time Domain ◽  
Dipole Source ◽  
Sh Wave ◽  
S Wave ◽  
High Fracture ◽  
S Waves ◽  
Angle Fracture ◽  
Dip Angle ◽  
Difference Time

Abstract In the process of dipole-source acoustic far-detection logging, the azimuth of the fracture outside the borehole can be determined with the assumption that the SH–SH wave is stronger than the SV–SV wave. However, in slow formations, the considerable borehole modulation highly complicates the dipole-source radiation of SH and SV waves. A 3D finite-difference time-domain method is used to investigate the responses of the dipole-source reflected shear wave (S–S) in slow formations and explain the relationships between the azimuth characteristics of the S–S wave and the source–receiver offset and the dip angle of the fracture outside the borehole. Results indicate that the SH–SH and SV–SV waves cannot be effectively distinguished by amplitude at some offset ranges under low- and high-fracture dip angle conditions, and the offset ranges are related to formation properties and fracture dip angle. In these cases, the fracture azimuth determined by the amplitude of the S–S wave not only has a $180^\circ $ uncertainty but may also have a $90^\circ $ difference from the actual value. Under these situations, the P–P, S–P and S–S waves can be combined to solve the problem of the $90^\circ $ difference in the azimuth determination of fractures outside the borehole, especially for a low-dip-angle fracture.

Regularization and datuming of seismic data by weighted, damped least squares

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. U67-U76 ◽  
Author(s):  
Robert J. Ferguson
Keyword(s):  
Least Squares ◽  
Seismic Data ◽  
Synthetic Data ◽  
Real Data ◽  
Structural Data ◽  
Irregular Sampling ◽  
Data Set ◽  
Near Surface ◽  
Damped Least Squares ◽  
Wavefield Extrapolation

The possibility of improving regularization/datuming of seismic data is investigated by treating wavefield extrapolation as an inversion problem. Weighted, damped least squares is then used to produce the regularized/datumed wavefield. Regularization/datuming is extremely costly because of computing the Hessian, so an efficient approximation is introduced. Approximation is achieved by computing a limited number of diagonals in the operators involved. Real and synthetic data examples demonstrate the utility of this approach. For synthetic data, regularization/datuming is demonstrated for large extrapolation distances using a highly irregular recording array. Without approximation, regularization/datuming returns a regularized wavefield with reduced operator artifacts when compared to a nonregularizing method such as generalized phase shift plus interpolation (PSPI). Approximate regularization/datuming returns a regularized wavefield for approximately two orders of magnitude less in cost; but it is dip limited, though in a controllable way, compared to the full method. The Foothills structural data set, a freely available data set from the Rocky Mountains of Canada, demonstrates application to real data. The data have highly irregular sampling along the shot coordinate, and they suffer from significant near-surface effects. Approximate regularization/datuming returns common receiver data that are superior in appearance compared to conventional datuming.

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