Phase Encoding of Shots in Pre-Stack Seismic Migration

Journal Article · Thu Sep 02 04:00:00 EDT 1999 · Journal of Geophysics

OSTI ID:12663

GHIGLIA, DENNIS C ^[1]; MORTON, SCOTT A; OBER, CURTIS C; ROMERO, LOUIS

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1. Sandia National Laboratories

Frequency-domain shot-record migration can produce higher quality images than Kirchhoff migration but typically at a greater cost. The computational cost of shot-record migration is the product of the number of shots in the survey and the expense of each individual migration. Many attempts to reduce this cost have focused on the speed of the individual migrations, trying to achieve a better trade-off between accuracy and speed. Another approach is to reduce the number of migrations. We investigate the simultaneous migration of shot records using frequency-domain shot-record migration algorithms. The difficulty with this approach is the production of so-called cross terms between unrelated shot and receiver wavefields, which generate unwanted artifacts or noise in the final image. To reduce these artifacts and obtain an image comparable in quality to the single-shot-per-migration result, we have introduced a process called phase encoding which shifts or disperses these cross terms. The process of phase encoding thus allows one to trade signal-to-noise ratio for the speed of migrating the entire survey. Several encoding functions and two application strategies have been tested. The first strategy, combining multiple shots per migration and using each shot only once, provides a reduction in computation directly related to the number of shots combined. The second strategy, performing multiple migrations of all the shots in the survey, provides a means to reduce the cross-term noise through stacking the resulting images. The additional noise in both strategies may be tolerated if it is no stronger than the inherent seismic noise in the migrated image, and if the final image is achieved with less cost.

• Research Organization: Sandia National Labs., Albuquerque, NM (US); Sandia National Labs., Livermore, CA (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 12663
• Report Number(s): SAND98-1463J revised
• Journal Information: Journal of Geophysics, Journal Name: Journal of Geophysics
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
ACCURACY
ALGORITHMS
CALCULATION METHODS
DATA ANALYSIS
IMAGE PROCESSING
SEISMIC SURVEYS
SIGNAL-TO-NOISE RATIO