The following matlab project contains the source code and matlab examples used for kirchhoff vortex contour dynamics simulation. Feb 04, 2016 this short video explains to a nonseismologist the concept of seismic migration. Geomages kpstm is a full kirchhoff diffraction summation algorithm that includes advanced antialiasing filters and is capable of imaging extremely large. Bg group plc or any of its respective subsidiaries, affiliates and associated companies or by any of their respective officers, employees or agents makes no representation or warranty, express or implied, in respect to the quality, accuracy or usefulness of this repository. By exploiting the spatial continuity of the impulse response, an efficient implementation of kirchhoff. Finite difference modeling of acoustic waves in matlab.
A library of matlab code for analysing postmigration prestack seismic data. In all cases, this desired migration was obtained using the phaseshift method with appropriate parameters. The impulse response of kirchhoff migration, although it may be very long, is continuos in space. Bohlen universitat kiel wrote the matlab tool for the trueamplitude. This process is necessary to overcome the limitations of geophysical methods imposed by areas of. This software package is based on the wavefront construction wfc technique that represents the same robustness. Parallel 3d prestack depth migration using recursive. A gui graphical user interface was designed to work with codes for convenience of. Piratheeben kulathilagan master thesis in geosciences discipline. In addition, the kirchhoff migration offers adaptability to irregular acquisition geometries, and flexibility in handling anisotropic and converted wave velocity models and surface topography. Computing prestack kirchhoff time migration on general. Migration operator aliasing and its effect on interpolation. Readers need a little background knowledge on kirchhoff migration and matlab programming language to follow the procedure mentioned in this paper easier. Kirchhoff migration integral has two inverse integrals in an.
Writing kirchhoff migrationmodelling in a matrix form crewes. Downloads are available as either unix gzipped tar files or windows zip files. Kirchhoff and fk migration to focus ground penetrating radar. On the other hand, vermeer 1995 has advocated a fine. Parallel programming in fortran 90 fortran 90 is a new fortran standard that has been implemented on a few massively parallel computers and a few vector computers.
There is currently no complete application that is built entirely with python i. The controversial topic of 3d spatial sampling and its impact on the final seismic image has generated several articles in the last few years advocating coarsely sampled acquisition geometries e. Kirchhoff migrations fast, accurate subsurface imaging and efficient velocity model building. Margrave abstract a matlab toolkit, called the afd package, has been written to model waves using acoustic finite differences. Reverse time migration is an ultrahighend prestack twoway waveequation migration for accurate imaging in and below areas with both great structural and velocity complexities, such as sedimentary areas with steep salt inclusions. Simulation for 2d reverse time migration rtm, with 100 shots and 100 sensors on the free surface. Computational imaging modalities support a simplification of the active architectures required in an imaging system and these approaches have been validated across the electromagnetic spectrum. Either c or fortran subroutine similar to matlab functions. Im not sure of what ways youre familiar with doing this, but i was taught to do it using matrices, and ive stuck with it.
A matlab version of equivalent offset migration eom john c. So this boils down to you being able to solve a system of four linear equations with four unknowns in matlab. A library of matlab code for analysing post migration prestack seismic data. The migration code is being developed in both matlab and c with careful attention to modular design. In this paper, a matlab software is presented that synthesizes 2d shot records with up to four flat reflectors with different velocities and then migrate them using. On your matlab prompt, type run kirmiggom to see a movie of migration as a function of maximum propagation angle amax. To investigate further the quality of the migrated cube, one representative. Kirchhoff prestack migration and modelling are linear operators. Search kirchhoff migration in matlab, 300 results found. Alternative processing software such as promax or vista is required to read the. An overview of all taskcentric pages can be found in the main taskcentric program list the most frequent question encountered from a new user is.
Two fitting routines are included which decompose the solutions into constituent linear eigenmodes. Here are the guidelines for geophysical software and algorithms papers. Subroutine kirchslow below is the best tutorial kirchhoff migrationmodeling program i could devise. Kirchhoff and fk migration to focus ground penetrating. Introduction the objective of this project is to develop a simple 2d kirchhoff migration program in java that can be used as a tutorial for others to see how a simple summationbased migration algorithm can be coded. However this image analysis depends on having sufficient spatial resolution in the backscattered signal. Geophysics department of geosciences faculty of mathematics and.
Reverse time migration is an ultrahighend prestack twoway waveequation migration for accurate imaging in and below areas with both great structural and velocity complexities, such as. However, it may of course be adapted to other uses, within the limits of the license. This short video explains to a nonseismologist the concept of seismic migration. In kirchhoff migration in practice, finitedifference migration in practice, frequencyspace migration in practice, and frequencywavenumber migration in practice, migration results of different algorithms using various parameters are compared with a desired migration. Array imaging using kirchhoff migration and beamforming, resolution theory for broad and narrow band array imaging in homogeneous media, topics in highfrequency, variable background imaging.
Thanks for contributing an answer to stack overflow. Image in and below areas with structural and velocity complexities. In this article, a new scalable 3d kirchhoff depth migration algorithm is presented on state of the art multicore cpu based cluster. Prestack time migration of 2d seismic records by the kirchhoff method. The algorithm will be described along with its assumptions and limitations. This paper introduces how to optimize a practical prestack kirchhoff time migration program by the compute unified device architecture cuda on a general purpose gpu gpgpu. Prestack kirchhoff time migration is applied via software written with matlab. A kirchhoff elliptic vortex is a 2d elliptical region or patch of uniform vorticity embedded in an inviscid, incompressible and irrotational fluid. The matlab program for crosscorrelating two length. The impulse response indicates that kirchhoff migration can accurately handle dips up to 90 degrees.
Kirchhoff migration methods are based on the diffraction summation technique, which sums the. Kirchhoff migration produces the section shown in figure 4. Note that migration can be limited to smaller dips. We implemented the contour dynamics algorithm in matlab in order to reexamine the evolution of the kirchhoff vortex, with an emphasis on the modes of the system. The massively parallel nature of graphics processing units has made them an attractive platform for some computationally tintensive algorithms. Apr 15, 2016 ground penetrating radar gpr based land mine detection has a main challenge of having an accurate image analysis method that is capable of reducing false alarms. Range migration algorithm file exchange matlab central. Seismic migration is the process by which seismic events are geometrically relocated in either space or time to the location the event occurred in the subsurface rather than the location that it was recorded at the surface, thereby creating a more accurate image of the subsurface. Although there are many methods offered by different scientists, there is not any complete migration focusing method that works perfectly for all scenarios. The seg advanced modeling program seam is a partnership between industry and seg designed to advance geophysical science and technology through the construction of subsurface models and generation of synthetic data sets. This repository includes a seismic migration routine for common offset gathers using a kirchhoff depth migration.
How to solve this big system of odes kirchhoffs law 2 with a trapezoidal implicit solver. This routine was an assignment for a university class and of course is highly specific. The main advance of fortran 90, with respect to fortran 77, is that arrays are treated as firstclass objects. This will allow us to use the parallel framework and libraries to quickly implement new algorithms. Common midpoint stack, which was state of the art until the early 1970s, was able to produce seismic images. Even though ground penetrating radar has been well studied and applied by many researchers for the last couple of decades, the focusing problem in the measured gpr images is still a challenging task. Writing kirchhoff migrationmodelling in a matrix form. Todays seismic processing centers need a broad portfolio. In this thesis, the norsar3d software has been employed to trace rays. This paper aims at getting better resolution by applying two migration algorithms.
Kirchhoff prestack time migration pstm can accurately image steep or overturned events, provided that turning rays and anisotropy are taken into account. Figure 3 illustrated that one output sample could be migrated. Kirchhoff vortex contour dynamics simulation file exchange. Solution of initial and boundary value problems, series solutions, laplace transforms, and nonlinear equations. A matlab version of equivalent offset migration eom. The idea of using kirchhoff modeling migration operators in the explicit forms is explained. Migration of seismic data moves dipping events to their correct positions. P51 2d kirchhoff prestack time migration of seismic synthetic. A library of matlab code for analysing postmigration pre.
General forms for excel is a very good software, study, work and research of large amounts of. Kirchhoff migration methods are based on the diffraction summation technique, which sums the seismic amplitudes along a. Equivalent offset migration is based on kirchhoff prestack migration but forms prestack migration gathers that are referred to as common scatterpoint csp gathers or. Ground penetrating radar gpr based land mine detection has a main challenge of having an accurate image analysis method that is capable of reducing false alarms. Kirchhoff vortex contour dynamics simulation in matlab. First you will limit the propagation angles in the subroutine, and then you will modify the routine to handle vz. Excel in matrix computation, and optimization algorithm of data fitting function is insufficient, combining excel and matlab are effective methods for dealing with comple. Kirchhoff migration offers adaptability to irregular acquisition. Davide teixeira, alex yeh and sampath gajawada, tgs. In order to keep this paper short, many aspects of kirchhoff migration and modelling are ignored. Kirchhoff time migration seismic processing software. Kirchhoff wavefront migration for efficient and accurate imaging 3d prestack depth migrations support multiple imaging. Threedimensional prestack kirchhoff migration of deep seismic.
Kirchhoff wavefront migration for efficient and accurate imaging. Modeling by demigration a feasibility study muhammad junaid yaqoob. Asking for help, clarification, or responding to other answers. Travel time approximations, including higherorder terms, to extend the applicability of kirchhoff time migration. How to solve this big system of odes kirchhoffs law 2. Jan 11, 2015 simulation for 2d reverse time migration rtm, with 100 shots and 100 sensors on the free surface. The layout shown is the one used for the kirchhoff migration algorithm described in the. Parallelization of 3d kirchhoff depth migration is challenging due to its high demand of compute time, memory, storage and io along with the need of their effective management. All methods of seismic migration involve the backpropagation or continuation of the seismic wavefield from the region where it was measured earths surface or along a borehole into the region to be imaged.
This article presents a method to run 3d kirchhoff prestack depth migration on. A gui graphical user interface was designed to work with codes for convenience of operator. This page presents a list of programs for seismic processing, imaging and analysis. It uses central finite difference schemes to approximate derivatives to the scalar wave equation. Also known as kirchhoff migration, a method of seismic migration that uses the integral form kirchhoff equation of the wave equation. Kirchhoff prestack time migration kpstm is an excellent tool that accurately images geological settings characterized by complex structure with relatively gentle velocity gradients.
General forms for excel is a very good software, study, work and research of large amounts of data may be stored in excel tables. For simplicity, we only show forward and reverse time wave propagation of the 1st, 50th, and. Osa phaseless computational imaging with a radiating. Finite difference modeling of acoustic waves in matlab carrie f. Analytical and numerical methods for solving ordinary differential equations arising in engineering applications. Implementation of kirchhoff prestack depth migration on gpu. However, the algorithms and the programs must still be designed carefully if good performance is to be obtained. Good that some stuff is available for beginners, they r not required to rub their heads to write from scratch. The dip on a migration impulse response is measured as the angle. Kirchhoff algorithms kirchhoff migration schneider, 1978 is applied to the data as a convolution with a space and time variant operator. The amplitude weighting of prestack kirchhoff migration is a very complex issue and is typically the topic of various solutions to the inversion problem.
Travel time approximations, including higherorder terms. A nice feature of this program is that it works ok while the. Although there are many methods offered by different scientists, there is not any complete migrationfocusing method that works perfectly for all scenarios. Kirchhoff prestack depth and time migration schlumberger. Prestack time migration of 2d seismic records by the. The kirchhoff migration is the most commonly used migration for depth and time imaging. Terwilliger1 abstract in this computer exercise you will modify the kirchho. One of the main advantages of kirchhoff migration is its ability to use arbitrary input or output geometry. Sep 22, 20 so this boils down to you being able to solve a system of four linear equations with four unknowns in matlab.
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