Mitigation of defocusing by statics and near-surface velocity errors by interferometric least-squares migration with a reference datum
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
Earth Science and Engineering Program
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AbstractImaging seismic data with an erroneous migration velocity can lead to defocused migration images. To mitigate this problem, we first choose a reference reflector whose topography is well-known from the well logs, for example. Reflections from this reference layer are correlated with the traces associated with reflections from deeper interfaces to get crosscorrelograms. Interferometric least-squares migration (ILSM) is then used to get the migration image that maximizes the crosscorrelation between the observed and the predicted crosscorrelograms. Deeper reference reflectors are used to image deeper parts of the subsurface with a greater accuracy. Results on synthetic and field data show that defocusing caused by velocity errors is largely suppressed by ILSM. We have also determined that ILSM can be used for 4D surveys in which environmental conditions and acquisition parameters are significantly different from one survey to the next. The limitations of ILSM are that it requires prior knowledge of a reference reflector in the subsurface and the velocity model below the reference reflector should be accurate.
CitationMitigation of defocusing by statics and near-surface velocity errors by interferometric least-squares migration with a reference datum 2016, 81 (4):S195 GEOPHYSICS
SponsorsThe research reported in this publication was supported by the King Abdullah University of Science and Technology (KAUST) in Thuwal, Saudi Arabia. We thank the sponsors of the CSIM consortium for their support. We would also like to thank the high-performance computing center of KAUST for providing access to their supercomputing facilities.
PublisherSociety of Exploration Geophysicists