Near-Surface Multi-Point Vibration Location Method Based on Seismic Depth Migration

2014 ◽  
Vol 577 ◽  
pp. 1211-1214
Author(s):  
Shan Hui Xu ◽  
Jian Guo ◽  
Pei Pei Li
Keyword(s):  
Seismic Waves ◽  
Seismic Wave Propagation ◽  
Source Location ◽  
Calculation Error ◽  
Near Surface ◽  
Depth Migration ◽  
Starting Position ◽  
Data Record ◽  
Migration Method ◽  
Seismic Depth Migration

This paper presents a method for multi-point vibration location near-surface. Unlike traditional source location technologies, it is not using travel times of seismic waves for positioning calculation, but according to the entire seismic data record, using the wave equation migration method to calculate the source location. Similar to exploration seismic, the records from a survey line within a certain period of time are data volumes with dimensions of time and ground coordinates. Based on the data, combined with surface seismic wave propagation characteristics, by using the improved seismic depth migration algorithm, the vibration energy will return to the starting position where exactly the source location is. The method can solve the problem of location calculation error by using traditional method when several vibration at the same time or continuous vibration occurs at some point.

Refraction wavefield migration

Geophysics ◽  
2020 ◽  
Vol 85 (6) ◽  
pp. Q27-Q37
Author(s):  
Yang Shen ◽  
Jie Zhang
Keyword(s):  
Signal To Noise Ratio ◽  
Surface Velocity ◽  
Data Set ◽  
Near Surface ◽  
Depth Migration ◽  
Reflection Data ◽  
Imaging Tool ◽  
Imaging Results ◽  
Migration Method ◽  
Single Method

Refraction methods are often applied to model and image near-surface velocity structures. However, near-surface imaging is very challenging, and no single method can resolve all of the land seismic problems across the world. In addition, deep interfaces are difficult to image from land reflection data due to the associated low signal-to-noise ratio. Following previous research, we have developed a refraction wavefield migration method for imaging shallow and deep interfaces via interferometry. Our method includes two steps: converting refractions into virtual reflection gathers and then applying a prestack depth migration method to produce interface images from the virtual reflection gathers. With a regular recording offset of approximately 3 km, this approach produces an image of a shallow interface within the top 1 km. If the recording offset is very long, the refractions may follow a deep path, and the result may reveal a deep interface. We determine several factors that affect the imaging results using synthetics. We also apply the novel method to one data set with regular recording offsets and another with far offsets; both cases produce sharp images, which are further verified by conventional reflection imaging. This method can be applied as a promising imaging tool when handling practical cases involving data with excessively weak or missing reflections but available refractions.

Depth migration with the near surface: A case study for mineral exploration in China

2019 ◽  
Vol 7 (4) ◽  
pp. T809-T817
Author(s):  
Guofeng Liu ◽  
Xiaohong Meng ◽  
Yu Liu
Keyword(s):  
Mineral Exploration ◽  
Velocity Model ◽  
Small Scale ◽  
Seismic Reflection Data ◽  
Near Surface ◽  
Imaging Quality ◽  
Depth Migration ◽  
Original Surface ◽  
Imaging Results ◽  
Migration Method

Seismic reflection data used in mineral exploration are usually of poor quality because of rough topography and small-scale heterogeneities. However, there is an increasing demand for accurate imaging processes that can obtain such data. Here, we have developed a practical rugged depth migration method based on the finite-difference one-way wave equation. It can be used to improve imaging quality when faced with rough topography and complex geologic features. First, synthetic data are used to illustrate the errors and problems that cause unsatisfactory imaging results. This is usually because no consideration is given to rough topography during conventional processing procedures. To address this, a depth migration method that begins with the rugged topography is introduced. It can be used to produce better images. Real data from mineral exploration activities in Fujian, China, are then used to demonstrate the practical use of this method. We also compare two computational processes: The first corrects the data back to the original surface and then builds a velocity model before conducting rugged depth migration; the second process involves performing rugged depth migration on processed data featuring a smoothed surface following short-wavelength static correction and residual correction. The imaging results indicate that the section obtained from the processed data has better quality. They also indicate that the imaging quality of the original surface is affected by the built velocity model, which cannot include near-surface and small-scale structures.

Gaussian beam migration of common-shot records

Geophysics ◽  
2005 ◽  
Vol 70 (4) ◽  
pp. S71-S77 ◽  
Author(s):  
Samuel H. Gray
Keyword(s):  
Gaussian Beam ◽  
Seismic Velocity ◽  
Data Sets ◽  
Model Data ◽  
Near Surface ◽  
Depth Migration ◽  
Migration Method ◽  
Gaussian Beam Migration ◽  
Wavefield Extrapolation ◽  
Natural Way

Gaussian beam migration is a depth migration method whose accuracy rivals that of migration by wavefield extrapolation — so-called “wave-equation migration” — and whose efficiency rivals that of Kirchhoff migration. This migration method can image complicated geologic structures, including very steep dips, in areas where the seismic velocity varies rapidly. However, applications of prestack Gaussian beam migration either have been limited to common-offset common-azimuth data volumes, and thus are inflexible, or suffer from multiarrival inaccuracies in a common-shot implementation. In order to optimize both the flexibility and accuracy of Gaussian beam migration, I present a common-shot implementation that handles multipathing in a natural way. This allows the migration of data sets that can include a variety of azimuths, and it allows a simplified treatment of near-surface issues. Application of this method to model data typical of Canadian Foothills structures and to model data that includes a complicated salt body demonstrates the accuracy and versatility of the migration.

A Plane Wave Depth Migration Method for Pre-Stack Seismic Data

2003 ◽  
Vol 46 (6) ◽  
pp. 1176-1185 ◽  
Author(s):  
Shengchang CHEN ◽  
Jingzhong CAO ◽  
Zaitian MA
Keyword(s):  
Plane Wave ◽  
Seismic Data ◽  
Depth Migration ◽  
Migration Method

scholarly journals Seismic wave propagation in anisotropic ice – Part 1: Elasticity tensor and derived quantities from ice-core properties

2015 ◽  
Vol 9 (1) ◽  
pp. 367-384 ◽  
Author(s):  
A. Diez ◽  
O. Eisen
Keyword(s):  
Seismic Waves ◽  
Dynamic Behaviour ◽  
Ice Core ◽  
Ice Cores ◽  
Seismic Wave Propagation ◽  
Elasticity Tensor ◽  
Reflection Coefficients ◽  
Seismic Velocities ◽  
Crystal Anisotropy ◽  
Elasticity Tensors

Abstract. A preferred orientation of the anisotropic ice crystals influences the viscosity of the ice bulk and the dynamic behaviour of glaciers and ice sheets. Knowledge about the distribution of crystal anisotropy is mainly provided by crystal orientation fabric (COF) data from ice cores. However, the developed anisotropic fabric influences not only the flow behaviour of ice but also the propagation of seismic waves. Two effects are important: (i) sudden changes in COF lead to englacial reflections, and (ii) the anisotropic fabric induces an angle dependency on the seismic velocities and, thus, recorded travel times. A framework is presented here to connect COF data from ice cores with the elasticity tensor to determine seismic velocities and reflection coefficients for cone and girdle fabrics. We connect the microscopic anisotropy of the crystals with the macroscopic anisotropy of the ice mass, observable with seismic methods. Elasticity tensors for different fabrics are calculated and used to investigate the influence of the anisotropic ice fabric on seismic velocities and reflection coefficients, englacially as well as for the ice–bed contact. Hence, it is possible to remotely determine the bulk ice anisotropy.

scholarly journals Vertical to Horizontal Spectral Ratio (VHSR) Response of Seismic Wave Propagation in a Homogeneous Elastic – Poroelastic Medium Using The Spectral Finite Element Method

2021 ◽  
Vol 11 (1) ◽  
pp. 95
Author(s):  
Sudarmaji Saroji ◽  
Budi Eka Nurcahya ◽  
Nivan Ramadhan Sugiantoro
Keyword(s):  
Finite Element Method ◽  
Elastic Medium ◽  
Seismic Waves ◽  
Low Frequency ◽  
Seismic Wave Propagation ◽  
P Wave ◽  
Poroelastic Medium ◽  
Compressional Waves ◽  
Spectral Finite Element Method ◽  
Spectral Finite Element

<p>Numerical modeling of 2D seismic wave propagation using spectral finite element method to estimate the response of seismic waves passing through the poroelastic medium from a hydrocarbon reservoir has been carried out. A hybrid simple model of the elastic - poroelastic - elastic with a mesoscopic scale element size of about 50cm was created. Seismic waves which was in the form of the ricker function are generated on the first elastic medium, propagated into the poroelastic medium and then transmitted to the second elastic medium. Pororoelastic medium is bearing hydrocarbon fluid in the form of gas, oil or water. Vertical and horizontal component of velocity seismograms are recorded on all mediums. Seismograms which are recorded in the poroelastic and second elastic medium show the existence of slow P compressional waves following fast P compressional waves that do not appear on the seismogram of the first elastic medium. The slow P wave is generated when the fast P wave enters the interface of the elastic - poroelastic boundary, propagated in the poroelastic medium and is transmited to the second elastic medium. The curves of Vertical to horizontal spectrum ratio (VHSR) which are observed from seismograms recorded in the poroelastic and the second elastic medium show that the peak of VHSR values at low frequency correlated with the fluid of poroelastic reservoir. The highest VHSR value at the low frequency which is recorded on the seismogram is above the 2.5 Hz frequency for reservoirs containing gas and oil in the second elastic medium, while for the medium containing water is the highest VHSR value is below the 2.5 Hz frequency.</p>

scholarly journals Basin Resonance and Seismic Hazard for Jakarta, Indonesia

2018 ◽  
Author(s):  
Athanasius Cipta ◽  
Phil Cummins ◽  
Masyhur Irsyam ◽  
Sri Hidayati
Keyword(s):  
Ground Motion ◽  
Seismic Waves ◽  
Response Spectrum ◽  
Capital City ◽  
Earthquake Ground Motion ◽  
Computational Domain ◽  
Near Surface ◽  
Earthquake Scenario ◽  
Design Response Spectrum ◽  
Intraslab Earthquake

We use earthquake ground motion modelling via Ground Motion Prediction Equations (GMPEs) and numerical simulation of seismic waves to consider the effects of site amplification and basin resonance in Jakarta, the capital city of Indonesia. While spectral accelerations at short periods are sensitive to near-surface conditions (i.e., Vs30), our results suggest that, for basins as deep as Jakarta&rsquo;s, available GMPEs cannot be relied upon to accurately estimate the effect of basin depth on ground motions at long periods (&gt;1 s). Amplitudes at such long periods are influenced by entrapment of seismic waves in the basin, resulting in longer duration of strong ground motion, and interference between incoming and reflected waves as well as focusing at basin edges may amplify seismic waves. In order to simulate such phenomena in detail, a basin model derived from a previous study is used as a computational domain for deterministic earthquake scenario modeling in a 2-dimensional cross-section. A Mw 9.0 megathrust, a Mw 6.5 crustal thrust and a Mw 7.0 instraslab earthquake are chosen as scenario events that pose credible threats to Jakarta, and the interactions with the basin of seismic waves generated by these events were simulated. The highest PGV amplifications are recorded at sites near the middle of the basin and near its southern edge, with maximum amplifications of PGV in the horizontal component of 200% for the crustal, 600% for the megathrust and 335% for the deep intraslab earthquake scenario, respectively. We find that the levels of ground motion response spectral acceleration fall below those of the 2012 Indonesian building Codes's design response spectrum for short periods (&lt; 1 s), but closely approach or may even exceed these levels for longer periods.

Extended local Rytov Fourier migration method

Geophysics ◽  
1999 ◽  
Vol 64 (5) ◽  
pp. 1535-1545 ◽  
Author(s):  
Lian‐Jie Huang ◽  
Michael C. Fehler ◽  
Peter M. Roberts ◽  
Charles C. Burch
Keyword(s):  
Phase Changes ◽  
Fast Fourier Transform Algorithm ◽  
Scalar Wave ◽  
Depth Migration ◽  
Frequency Space ◽  
Rytov Approximation ◽  
Migration Method ◽  
The Stability ◽  
Wavefield Extrapolation ◽  
Lateral Variations

We develop a novel depth‐migration method termed the extended local Rytov Fourier (ELRF) migration method. It is based on the scalar wave equation and a local application of the Rytov approximation within each extrapolation interval. Wavefields are Fourier transformed back and forth between the frequency‐space and frequency‐wavenumber domains during wavefield extrapolation. The lateral slowness variations are taken into account in the frequency‐space domain. The method is efficient due to the use of a fast Fourier transform algorithm. Under the small angle approximation, the ELRF method leads to the split‐step Fourier (SSF) method that is unconditionally stable. The ELRF method and the extended local Born Fourier (ELBF) method that we previously developed can handle wider propagation angles than the SSF method and account for the phase and amplitude changes due to the lateral variations of slowness, whereas the SSF method only accounts for the phase changes. The stability of the ELRF method is controlled more easily than that of the ELBF method.

Crosscoherence-based interferometry for the retrieval of first arrivals and subsequent tomographic imaging of differential weathering

Geophysics ◽  
2019 ◽  
Vol 84 (4) ◽  
pp. Q37-Q48 ◽  
Author(s):  
Joachim Place ◽  
Deyan Draganov ◽  
Alireza Malehmir ◽  
Christopher Juhlin ◽  
Chris Wijns
Keyword(s):  
Seismic Waves ◽  
Seismic Velocity ◽  
Signal To Noise Ratio ◽  
Seismic Profile ◽  
Seismic Interferometry ◽  
Near Surface ◽  
Tomographic Images ◽  
Traveltime Tomography ◽  
Seismic Methods ◽  
Source Signal

Exhumation of crust exposes rocks to weathering agents that weaken the rocks’ mechanical strength. Weakened rocks will have lower seismic velocity than intact rocks and can therefore be mapped using seismic methods. However, if the rocks are heavily weathered, they will attenuate controlled-source seismic waves to such a degree that the recorded wavefield would become dominated by ambient noise and/or surface waves. Therefore, we have examined the structure of differential weathering by first-break traveltime tomography over a seismic profile extending approximately 3.5 km and acquired at a mining site in Zambia using explosive sources and a source based on the swept-impact seismic technique (SIST). Seismic interferometry has been tested for the retrieval of supervirtual first arrivals masked by uncorrelated noise. However, use of crosscorrelation in the retrieval process makes the method vulnerable to changes in the source signal (explosives and SIST). Thus, we have developed a crosscoherence-based seismic-interferometry method to tackle this shortcoming. We investigate the method’s efficiency in retrieving first arrivals and, simultaneously, correctly handling variations in the source signal. Our results illustrate the superiority of the crosscoherence- over crosscorrelation-based method for retrieval of the first arrivals, especially in alleviating spurious ringyness and in terms of the signal-to-noise ratio. These benefits are observable in the greater penetration depth and the improved resolution of the tomography sections. The tomographic images indicate isolated bodies of higher velocities, which may be interpreted as fresh rocks embedded into a heavily weathered regolith, providing a conspicuous example of differential weathering. Our study advances the potential of seismic methods for providing better images of the near surface (the critical zone).

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