A new insight of beam-ray imaging method based on the stationary-phase principle and unified Kirchhoff imaging theory: An example of CRS stack and Prestack time migration

We have improved the so-called deabsorption prestack time migration (PSTM) by introducing a dip-angle domain stationary-phase implementation. Deabsorption PSTM compensates absorption and dispersion via an actual wave propagation path using effective [Formula: see text] parameters that are obtained during migration. However, noises induced by the compensation degrade the resolution gained and deabsorption PSTM requires more computational effort than conventional PSTM. Our stationary-phase implementation improves deabsorption PSTM through the determination of an optimal migration aperture based on an estimate of the Fresnel zone. This significantly attenuates the noises and reduces the computational cost of 3D deabsorption PSTM. We have estimated the 2D Fresnel zone in terms of two dip angles through building a pair of 1D migrated dip-angle gathers using PSTM. Our stationary-phase QPSTM (deabsorption PSTM) was implemented as a two-stage process. First, we used conventional PSTM to obtain the Fresnel zones. Then, we performed deabsorption PSTM with the Fresnel-zone-based optimized migration aperture. We applied stationary-phase QPSTM to a 3D field data. Comparison with synthetic seismogram generated from well log data validates the resolution enhancements.

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Prestack time migration of nonplanar data: Improving topography prestack time migration with dip-angle domain stationary-phase filtering and effective velocity inversion

Geophysics ◽

10.1190/geo2016-0087.1 ◽

2017 ◽

Vol 82 (3) ◽

pp. S235-S246 ◽

Cited By ~ 6

Author(s):

Jincheng Xu ◽

Jianfeng Zhang

Keyword(s):

Stationary Phase ◽

Real Data ◽

Data Set ◽

Near Surface ◽

Velocity Inversion ◽

Effective Velocity ◽

Time Migration ◽

Static Corrections ◽

Prestack Time Migration ◽

Dip Angle

We have developed a modified prestack time migration (PSTM) approach that can directly image nonplanar data by using two effective velocity parameters above and below a datum. The proposed extension improves the so-called topography PSTM by introducing a dip-angle domain stationary-phase migration (or filtering) and combining effective velocity inversion with the residual static corrections. The stationary-phase migration to constrain the imaging aperture within Fresnel zones significantly improves the signal-to-noise ratio (S/N) of the image gathers, especially in the presence of steeply dipping structures. This helps to extract an accurate residual moveout from the common shot and receiver image gathers, and the surface-consistent residual statics hidden in these image gathers can be simultaneously obtained from an inversion process. As a result, the final migrated images show higher S/N and are better focused than the conventional topography PSTM. The proposed technique can handle rugged topography, especially in the presence of high near-surface velocities, without the need for prior elevation static corrections. The SEG foothills overthrust model and a real data set acquired on a piedmont zone are used to validate the modified topography PSTM. Synthetic and field data examples are obtained with good results.

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Phaseless Imaging by Reverse Time Migration: Acoustic Waves

Numerical Mathematics Theory Methods and Applications ◽

10.4208/nmtma.2017.m1617 ◽

2017 ◽

Vol 10 (1) ◽

pp. 1-21 ◽

Cited By ~ 23

Author(s):

Zhiming Chen ◽

Guanghui Huang

Keyword(s):

Acoustic Waves ◽

Numerical Experiments ◽

Cross Correlation ◽

Scattering Data ◽

Imaging Method ◽

Total Field ◽

Reverse Time ◽

Reverse Time Migration ◽

Time Migration ◽

Imaging Results

AbstractWe propose a reliable direct imaging method based on the reverse time migration for finding extended obstacles with phaseless total field data. We prove that the imaging resolution of the method is essentially the same as the imaging results using the scattering data with full phase information when the measurement is far away from the obstacle. The imaginary part of the cross-correlation imaging functional always peaks on the boundary of the obstacle. Numerical experiments are included to illustrate the powerful imaging quality

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3D constraints and finite-difference modeling of massive sulfide deposits: The Kristineberg seismic lines revisited, northern Sweden

Geophysics ◽

10.1190/geo2011-0466.1 ◽

2012 ◽

Vol 77 (5) ◽

pp. WC69-WC79 ◽

Cited By ~ 21

Author(s):

Mahdieh Dehghannejad ◽

Alireza Malehmir ◽

Christopher Juhlin ◽

Pietari Skyttä

Keyword(s):

Finite Difference ◽

Seismic Data ◽

Massive Sulfide ◽

Northern Sweden ◽

Seismic Reflection Data ◽

Sulfide Deposits ◽

Time Migration ◽

Massive Sulfide Deposits ◽

Prestack Time Migration ◽

Seismic Lines

The Kristineberg mining area in the western part of the Skellefte ore district is the largest base metal producer in northern Sweden and currently the subject of extensive geophysical and geologic studies aimed at constructing 3D geologic models. Seismic reflection data form the backbone of the geologic modeling in the study area. A geologic cross section close to the Kristineberg mine was used to generate synthetic seismic data using acoustic and elastic finite-difference algorithms to provide further insight about the nature of reflections and processing challenges when attempting to image the steeply dipping structures within the study area. Synthetic data suggest processing artifacts manifested themselves in the final 2D images as steeply dipping events that could be confused with reflections. Fewer artifacts are observed when the data are processed using prestack time migration. Prestack time migration also was performed on high-resolution seismic data recently collected near the Kristineberg mine and helped to image a high-amplitude, gently dipping reflection occurring stratigraphically above the extension of the deepest Kristineberg deposit. Swath 3D processing was applied to two crossing seismic lines, west of the Kristineberg mine, to provide information on the 3D geometry of an apparently flat-lying reflection observed in both of the profiles. The processing indicated that the reflection dips about 30° to the southwest and is generated at the contact between metasedimentary and metavolcanic rocks, the upper part of the latter unit being the most typical stratigraphic level for the massive sulfide deposits in the Skellefte district.

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Seismic diffraction separation in the near-surface: Detection of high contrast voids in unconsolidated soils

Geophysics ◽

10.1190/geo2020-0366.1 ◽

2021 ◽

pp. 1-72

Author(s):

Parsa Bakhtiari Rad ◽

Craig J. Hickey

Keyword(s):

Soft Soil ◽

Processing Parameters ◽

Imaging Method ◽

Data Sets ◽

High Contrast ◽

Near Surface ◽

Time Migration ◽

Diffraction Imaging ◽

Dip Angle ◽

Scattering Time

Seismic diffractions carry the signature of near-surface high-contrast anomalies and need to be extracted from the data to complement the reflection processing and other geophysical techniques. Since diffractions are often masked by reflections, surface waves and noise, a careful diffraction separation is required as a first step for diffraction imaging. A multiparameter time-imaging method is employed to separate near-surface diffractions. The implemented scheme makes use of the wavefront attributes that are reliable fully data-derived processing parameters. To mitigate the effect of strong noise and wavefield interference in near-surface data, the proposed workflow incorporates two wavefront-based parameters, dip angle and coherence, as additional constraints. The output of the diffraction separation is a time trace-based stacked section that provides the basis for further analysis and applications such as time migration. To evaluate the performance of the proposed wavefront-based workflow, it is applied to two challenging field data sets that were collected over small culverts in very near-surface soft soil environments. The results of the proposed constrained workflow and the existing unconstrained approach are presented and compared. The proposed workflow demonstrates superiority over the existing method by attenuating more reflection and noise, leading to improved diffraction separation. The abundance of unmasked diffractions reveal that the very near-surface is highly scattering. Time migration is carried out to enhance the anomaly detection by focusing of the isolated diffractions. Although strong diffractivity is observed at the approximate location of the targets, there are other diffracting zones observed in the final sections that might bring uncertainties for interpretation.

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Some Aspects of Seismic Data Reverse Time Migration for Salt Tectonics Geology of the Dnieper-Donets Basin

10.2118/208531-ms ◽

2021 ◽

Author(s):

Pavlo Kuzmenko ◽

Viktor Buhrii ◽

Carlo D'Aguanno ◽

Viktor Maliar ◽

Hrigorii Kashuba ◽

...

Keyword(s):

Seismic Data ◽

Full Range ◽

Donets Basin ◽

Salt Tectonics ◽

Imaging Method ◽

Reverse Time ◽

Reverse Time Migration ◽

Time Migration ◽

Seismic Image ◽

Complex Geology

Abstract Processing of the seismic data acquired in areas of complex geology of the Dnieper-Donets basin, characterized by the salt tectonics, requires special attention to the salt dome interpretation. For this purpose, Kirchhoff Depth Imaging and Reverse Time Migration (RTM) were applied and compared. This is the first such experience in the Dnieper-Donets basin. According to international experience, RTM is the most accurate seismic imaging method for steep and vertical geological (acoustic contrast) boundaries. Application of the RTM on 3D WAZ land data is a great challenge in Dnieper-Donets Basin because of the poor quality of the data with a low signal-to-noise ratio and irregular spatial sampling due to seismic acquisition gaps and missing traces. The RTM algorithm requires data, organized to native positions of seismic shots. For KPSDM we used regularized data after 5D interpolation. This affects the result for near salt reflection. The analysis of KPSDM and RTM results for the two areas revealed the same features. RTM seismic data looked more smoothed, but for steeply dipping reflections, lateral continuity of reflections was much improved. The upper part (1000 m) of the RTM has shadow zones caused by low fold. Other differences between Kirchhoff data and RTM are in the spectral content, as the former is characterized by the full range of seismic frequency spectrum. Conversely, beneath the salt, the RTM has reflections with steep dips which are not observed on the KPSDM. It is possible to identify new prospects using the RTM seismic image. Reverse Time Migration of 3D seismic data has shown geologically consistent results and has the potential to identify undiscovered hydrocarbon traps and to improve salt flank delineation in the complex geology of the Dnieper-Donets Basin's salt domes.

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