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Source free converted wave reverse time migration; formulation and limitations

Yue Du, Elita Yunyue Li, Jizhong Yang, Arthur Cheng and Fang Xinding
Source free converted wave reverse time migration; formulation and limitations
Geophysics (January 2019) 84 (1): S17-S27

Abstract

The source-free converted-wave (SFCW) reverse time migration is an alternative way to image the subsurface when the source information is missing or the overburden velocities are complex. However, it is challenging due to the lack of source-wavefield constraints. We have derived the SFCW imaging condition from the first gradients of waveform matching objective functions using a set of coupled P- and S-potential equations and small-perturbation approximations. We found that the images obtained from this SFCW imaging condition are second-order approximations to the shear-modulus perturbations. The images produced by the proposed imaging condition are free of the polarity reversal effects and have clear physical meanings. We also find that the acoustic wave equations can be used to back propagate the recorded P- and S-potentials, and the resulting images have the same kinematic accuracy and fewer unphysical mode-conversion artifacts than the SFCW images obtained by the elastic wave equations. Using multiple numerical examples, we determine the accuracy of our formulations, analyze the resolution and artifacts on the resulting images, and develop the limitations of the proposed method.


ISSN: 0016-8033
EISSN: 1942-2156
Coden: GPYSA7
Serial Title: Geophysics
Serial Volume: 84
Serial Issue: 1
Title: Source free converted wave reverse time migration; formulation and limitations
Affiliation: National University of Singapore, Department of Civil and Environmental Engineering, Singapore, Singapore
Pages: S17-S27
Published: 201901
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 27
Accession Number: 2019-006917
Categories: Applied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendices
Illustration Description: illus.
Secondary Affiliation: Southern University of Science and Technology, CHN, China
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 201906
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