Least-squares reverse time migration of multiples

Handle URI:
http://hdl.handle.net/10754/575590
Title:
Least-squares reverse time migration of multiples
Authors:
Zhang, Dongliang; Schuster, Gerard T. ( 0000-0001-7532-1587 )
Abstract:
The theory of least-squares reverse time migration of multiples (RTMM) is presented. In this method, least squares migration (LSM) is used to image free-surface multiples where the recorded traces are used as the time histories of the virtual sources at the hydrophones and the surface-related multiples are the observed data. For a single source, the entire free-surface becomes an extended virtual source where the downgoing free-surface multiples more fully illuminate the subsurface compared to the primaries. Since each recorded trace is treated as the time history of a virtual source, knowledge of the source wavelet is not required and the ringy time series for each source is automatically deconvolved. If the multiples can be perfectly separated from the primaries, numerical tests on synthetic data for the Sigsbee2B and Marmousi2 models show that least-squares reverse time migration of multiples (LSRTMM) can significantly improve the image quality compared to RTMM or standard reverse time migration (RTM) of primaries. However, if there is imperfect separation and the multiples are strongly interfering with the primaries then LSRTMM images show no significant advantage over the primary migration images. In some cases, they can be of worse quality. Applying LSRTMM to Gulf of Mexico data shows higher signal-to-noise imaging of the salt bottom and top compared to standard RTM images. This is likely attributed to the fact that the target body is just below the sea bed so that the deep water multiples do not have strong interference with the primaries. Migrating a sparsely sampled version of the Marmousi2 ocean bottom seismic data shows that LSM of primaries and LSRTMM provides significantly better imaging than standard RTM. A potential liability of LSRTMM is that multiples require several round trips between the reflector and the free surface, so that high frequencies in the multiples suffer greater attenuation compared to the primary reflections. This can lead to lower resolution in the migration image compared to that computed from primaries. Another liability is that the multiple migration image is more down-dip limited than the standard primaries migration image. Finally, if the surface-related multiple elimination method is imperfect and there are strong multiples interfering with the primaries, then the resulting LSRTMM image can be significantly degraded. We conclude that LSRTMM can be a useful complement, not a replacement, for RTM of primary reflections.
KAUST Department:
Physical Sciences and Engineering (PSE) Division; Physical Sciences and Engineering (PSE) Division; Environmental Science and Engineering Program; Earth Science and Engineering Program
Publisher:
Society of Exploration Geophysicists
Journal:
GEOPHYSICS
Issue Date:
6-Dec-2013
DOI:
10.1190/GEO2013-0156.1
Type:
Article
ISSN:
0016-8033; 1942-2156
Sponsors:
We thank the KAUST Supercomputing Lab for the computer cycles they donated to this project. We are especially grateful for the use of the SHAHEEN supercomputer. We also acknowledge the support of the CSIM sponsors (http://csim.kaust.edu.sa). We thank Yi Luo, Yike Liu, Yue Wang, and Yonghe Sun for their constructive suggestion and comments. We would like to especially thank Ge Zhan, Wei Dai, and Xin Wang for their help with this paper.
Appears in Collections:
Articles; Environmental Science and Engineering Program; Physical Sciences and Engineering (PSE) Division; Earth Science and Engineering Program

Full metadata record

DC FieldValue Language
dc.contributor.authorZhang, Dongliangen
dc.contributor.authorSchuster, Gerard T.en
dc.date.accessioned2015-08-24T08:33:36Zen
dc.date.available2015-08-24T08:33:36Zen
dc.date.issued2013-12-06en
dc.identifier.issn0016-8033en
dc.identifier.issn1942-2156en
dc.identifier.doi10.1190/GEO2013-0156.1en
dc.identifier.urihttp://hdl.handle.net/10754/575590en
dc.description.abstractThe theory of least-squares reverse time migration of multiples (RTMM) is presented. In this method, least squares migration (LSM) is used to image free-surface multiples where the recorded traces are used as the time histories of the virtual sources at the hydrophones and the surface-related multiples are the observed data. For a single source, the entire free-surface becomes an extended virtual source where the downgoing free-surface multiples more fully illuminate the subsurface compared to the primaries. Since each recorded trace is treated as the time history of a virtual source, knowledge of the source wavelet is not required and the ringy time series for each source is automatically deconvolved. If the multiples can be perfectly separated from the primaries, numerical tests on synthetic data for the Sigsbee2B and Marmousi2 models show that least-squares reverse time migration of multiples (LSRTMM) can significantly improve the image quality compared to RTMM or standard reverse time migration (RTM) of primaries. However, if there is imperfect separation and the multiples are strongly interfering with the primaries then LSRTMM images show no significant advantage over the primary migration images. In some cases, they can be of worse quality. Applying LSRTMM to Gulf of Mexico data shows higher signal-to-noise imaging of the salt bottom and top compared to standard RTM images. This is likely attributed to the fact that the target body is just below the sea bed so that the deep water multiples do not have strong interference with the primaries. Migrating a sparsely sampled version of the Marmousi2 ocean bottom seismic data shows that LSM of primaries and LSRTMM provides significantly better imaging than standard RTM. A potential liability of LSRTMM is that multiples require several round trips between the reflector and the free surface, so that high frequencies in the multiples suffer greater attenuation compared to the primary reflections. This can lead to lower resolution in the migration image compared to that computed from primaries. Another liability is that the multiple migration image is more down-dip limited than the standard primaries migration image. Finally, if the surface-related multiple elimination method is imperfect and there are strong multiples interfering with the primaries, then the resulting LSRTMM image can be significantly degraded. We conclude that LSRTMM can be a useful complement, not a replacement, for RTM of primary reflections.en
dc.description.sponsorshipWe thank the KAUST Supercomputing Lab for the computer cycles they donated to this project. We are especially grateful for the use of the SHAHEEN supercomputer. We also acknowledge the support of the CSIM sponsors (http://csim.kaust.edu.sa). We thank Yi Luo, Yike Liu, Yue Wang, and Yonghe Sun for their constructive suggestion and comments. We would like to especially thank Ge Zhan, Wei Dai, and Xin Wang for their help with this paper.en
dc.publisherSociety of Exploration Geophysicistsen
dc.titleLeast-squares reverse time migration of multiplesen
dc.typeArticleen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentEnvironmental Science and Engineering Programen
dc.contributor.departmentEarth Science and Engineering Programen
dc.identifier.journalGEOPHYSICSen
kaust.authorZhang, Dongliangen
kaust.authorSchuster, Gerard T.en
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