• Title/Summary/Keyword: Kirchhoff migration

Search Result 11, Processing Time 0.175 seconds

Kirchhoff Prestack Depth Migration for the Complex Structure Using One-Way Wave Equation (일방향 파동방정식을 이용한 복잡한 구조의 키리히호프 중합전 심도구조보정)

  • Ko, Seung-Won;Yang, Seung-Jin
    • Geophysics and Geophysical Exploration
    • /
    • v.5 no.1
    • /
    • pp.18-22
    • /
    • 2002
  • As a single arrival traveltime, maximum energy arrival traveltime has been known as the most proper operator for Kirchhoff migration. In case of the model having the simple structure, both the first arrival traveltime and the maximum energy arrival traveltime can be used as the correct operators for Kirchhoff migration. However for some model having the complex and high velocity contrast structure, the migration using the first arrival traveltime can't give the correct depth section. That is, traveltime to be required in Kirchhoff migration is the maximum energy traveltime, but, needs considerably more calculation time than that of first arrival. In this paper, we propose the method for calculating the traveltime approximated to the maximum energy arrival using one-way wave equation. After defining the WAS(Wrap Around Suppression) factor to be used for calculating the first arrival traveltime using one-way wave equation as the function of lateral grid interval and depth and considering the delay time of source wavelet. we calculate the traveltime approximated to the maximum energy arrival. to verify the validity of this traveltime, we applied this to the migraion for simple structure and complex structure and compared the depth section with that obtained by using the first arrival traveltime.

Kirchhoff prestack depth migration for gas hydrate seismic data set (가스 하이드레이트 자료에 대한 중합전 키르히호프 심도 구조보정)

  • Hien, Doan Huy;Jang, Seong-Hyung;Kim, Young-Wan;Suh, Sang-Yong
    • 한국신재생에너지학회:학술대회논문집
    • /
    • /
    • pp.493-496
    • /
    • 2007
  • Korean Institute of Geosciences and Mineral Resources (KIGAM) has studied on gas hydrate in the Ulleung Basin, East sea of Korea since 1997. Most of all, a evidence for existence of gas hydrate, possible new energy resources, in seismic reflection data is bottom simulating reflection (BSR) which parallel to the sea bottom. Here we conducted the conventional data processing for gas hydrate data and Kirchhoff prestack depth migration. Kirchhoff migration is widely used for pre- and post-stack migration might be helpful to better image as well as to get the geological information. The processed stack image by GEOBIT showed some geological structures such as faults and shallow gas hydrate seeping area indicated by strong BSR. The BSR in the stack image showed at TWT 3.07s between shot gather No 3940 to No 4120. The estimated gas seeping area occurred at the shot point No 4187 to No 4203 and it seems to have some minor faults at shot point No 3735, 3791, 3947 and 4120. According to the result of depth migration, the BSR showed as 2.3km below the sea bottom.

  • PDF

A Study on the Detection of Small Cavity Located in the Hard Rock by Crosswell Seismic Survey (경암 내 소규모 공동 탐지를 위한 시추공간 탄성파탐사 기법의 적용성 연구)

  • Ko, Kwang-Beom;Lee, Doo-Sung
    • Geophysics and Geophysical Exploration
    • /
    • v.6 no.2
    • /
    • pp.57-63
    • /
    • 2003
  • For the dectection of small cavity in the hard rock, we investigated the feasibility of crosswell travel-time tomography and Kirchhoff migration technique. In travel-time tomography, first arrival anomaly caused by small cavity was investigated by numerical modeling based on the knowledge of actual field information. First arrival delay was very small (<0.125 msec) and detectable receiver offset range was limited to 4m with respect to $1\%$ normalized first arrival anomaly. As a consequence, it was turned out that carefully designed survey array with both sufficient narrow spatial spacing and temporal (<0.03125 msec) sampling were required for small cavity detection. Also, crosswell Kirchhoff migration technique was investigated with both numerical and real data. Stack section obtained by numerical data shows the good cavity image. In crosswell seismic data, various unwanted seismic events such as direct wave and various mode converted waves were alto recorded. To remove these noises und to enhance the diffraction signal, combination of median and bandpass filtering was applied and prestack and stacked migration images were created. From this, we viewed the crosswell migration technique as one of the adoptable method for small cavity detection.

Improvement of Migration Image for Ocean-bottom Seismic Data using Wavefield Separation and Mirror Imaging (파동장 분리와 미러 이미징을 이용한 해저면 탄성파 탐사 자료의 참반사 보정 영상 개선)

  • Lee, Ganghoon;Pyun, Sukjoon
    • Geophysics and Geophysical Exploration
    • /
    • v.21 no.2
    • /
    • pp.112-124
    • /
    • 2018
  • Ocean-bottom seismic survey is a seismic acquisition technique which measures data by installing 4-component receiver on the sea floor. It can produce more improved data in quality than any other acquisition techniques. In the ocean-bottom seismic survey, however, the number of receivers is limited due to high cost. Since only a small number of receivers are used for acquisition, ocean-bottom seismic data may suffer from discontinuities of events over traces, which can result in spatial aliasing. In this paper, we implemented Kirchhoff migration using mirror-imaging algorithm to improve the quality of ocean-bottom seismic image. In order to implement the mirror imaging algorithm, the seismograms should be separated into up-going and down-going wavefields and the down-going wavefield should be used for migration. In this paper, we use the P-Z summation method to separate the wavefield. Numerical examples show that the migration results using mirror imaging algorithm have wider illumination than the conventional migration, especially in the shallow layers.

3-D reverse-time migration using acoustic wave equation: An experience of SEG/EAGE salt data set

  • Yoon, Kwang-Jin;Shin, Chang-Soo;Hong, Soon-Duk;Yang, Seung-Jin;Suh, Sang-Yong
    • Proceedings of the KSEEG Conference
    • /
    • /
    • pp.156-158
    • /
    • 2002
  • Reverse-time migration has no dip limitations and one of the most promising methods to preserve true amplitudes. We applied 3-D prestack reverse time migration based on a pseudo-spectral implementation of the acoustic wave equation to the SEG/EAGE salt dome synthetic data set. We were able to illuminate sub salt reflectors of the SEG/EAGE salt model that were barely observable in the Kirchhoff migration images. Using the pseudo-spectral modeling technique, we could implement reverse-time migration within the core memory, which could be equipped to a personal computer.

  • PDF

Imaging of Ground Penetrating Radar Data Using 3-D Kirchhoff Migration (3차원 Kirchhoff 구조보정을 이용한 지표레이다자료의 영상화)

  • Cho, Dong-Ki;Suh, Jung-Hee;Choi, Yoon-Kyoung
    • Geophysics and Geophysical Exploration
    • /
    • v.5 no.3
    • /
    • pp.185-192
    • /
    • 2002
  • We made a study of 3-D migration which could precisely image data of GPR (Ground Penetrating Radar) applied to NDT (Non-Destructive Test) field for the inspection of structural safety. In this study, we obtained 3-D migrated images of important targets in structuresurvey (e.g. steel pipes, cracks) by using 3-D Kirchhoff prestack depth migration scheme developed for seismic data processing. For a concrete model consisting of steel pipe and void, the targets have been well defined with opposite amplitude according to the parameters of the targets. And migrated images using Parallel-Broadside array (XX configuration) have shown higher resolution than those using Perpendicular-Broadside array (YY configuration) when steel pipes had different sizes. Therefore, it is required to analyze the migrated image of XX configuration as well as that of general YY configuration in order to get more accurate information. As the last stage, we chose a model including two steel pipes which cross each other. The upper pipe has been resolved clearly but the lower has been imaged bigger than the model size due to the high conductivity of the upper steel.

Subsurface Imaging using Headwave Stacking (선두파 중합을 이용한 천부지층의 영상화)

  • Park Jung-Jae;Ko Seung-Won;Shin Chang-Soo;Suh Jung-Hee
    • Geophysics and Geophysical Exploration
    • /
    • v.5 no.3
    • /
    • pp.178-184
    • /
    • 2002
  • For economy and convenience, seismic refraction survey is widely used in surveying for large civil engineering work. The purpose of this study is to obtain the numerical responses of various models using Kirchhoff migration, and to analyze its application to the real data processing. Synthetic traveltime curve was calculated by vidale's algorithm, and various models such as 2 or 3 layer model and irregular topography model are tested to simulate the response of real structure. In order to compare the effect of initial velocity model, true velocity models, inversion results by tomography, smooth velocity models are used as an initial guess. The responses of model data show that the algorithm of this study is more sensitive to initial velocity model than the reflection survey, so choosing a suitable initial velocity model will be the most important thing in real data processing.

Data Processing using Anisotropic Analysis for the Long-offset Marine Seismic Data of the East Sea, Korea (동해 해역 원거리 해양탄성파 탐사자료의 이방성 분석을 이용한 전산처리)

  • Joo, Yonghwan;Kim, Byoung-yeop
    • Geophysics and Geophysical Exploration
    • /
    • v.23 no.1
    • /
    • pp.13-21
    • /
    • 2020
  • The acquisition and processing of long-offset data are essential for imaging deep geological structures in marine seismic surveys. It is challenging to derive an accurate subsurface image by employing conventional data processing to long-offset data owing to the normal moveout (NMO) stretch and non-hyperbolic moveout phenomena induced by seismic anisotropy. In 2017, the Korea Institute of Geoscience and Mineral Resources conducted a simultaneous two-dimensional multichannel streamer and ocean-bottom seismic survey using a 5.7-km streamer and an ocean-bottom seismometer to identify the deep geological structure of the Ulleung Basin. Herein, the actual geological subsurface structure was obtained via the sequential iterative updating of the velocity and anisotropic parameters of the long-offset data obtained using a multichannel streamer, and anisotropic prestack Kirchhoff migration was performed using the updated velocity and anisotropic parameters as input parameters. As a result, the reflection energy in the long-offset traces, which showed non-hyperbolic moveout owing to seismic anisotropy, was well aligned horizontally and NMO stretches were also reduced. Thus, a more precise and accurate migrated image was obtained, minimizing the distortion of reflectors and mispositioned reflection energy.

Non-destructive testing of historical masonry using radar tomography (레이더 토모그래피에 의한 석조문화재 비파괴 검사)

  • Cha, Young-Ho;Kang, Jong-Suk;Choi, Yun-Gyeong;Suh, Jung-Hee;Bae, Byeong-Seon
    • 한국지구물리탐사학회:학술대회논문집
    • /
    • /
    • pp.138-156
    • /
    • 2004
  • GPR(Ground Penetrating Radar) was used for imaging the interior of the historical masonry such as stone pagoda in order to provide the basic information of safely inspection. The scope of the imaging was restricted to the foundation part of stone pagoda that transferred the load of the pagoda to the ground. Kirchhoff migration and traveltime tomography was used for imaging the outer stone and the inside of stone pagoda, respectively. From the migrated images, we could measure the thickness and the shape of the boundaries of the outer stone in the foundation part. From the reconstructed tomograms for the physical model, we could get the GPR propagation velocity distribution and exactly find the position of the air in the model and calculate the average velocity with respect to the different filling materials. The properties and the shape of the interior materials of stone pagoda can be basic informations for the safety inspection.

  • PDF