GESGB Online Talk | Survey Design for Surveys Incorporating FWI

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Event Information

Speaker: Dave Monk

Topic: Survey Design for Surveys Incorporating FWI

Abstract

The increasing use of Full Waveform Inversion (FWI) in 3D surveys potentially changes the way that surveys should be designed to take advantage of FWI for both velocity determination and for imaging. It is possible to parameterize survey designs for increased cost effectiveness without degradation of the final data, and include the data that is required for FWI.

Conventional survey design yields limited imaging in the shallow section when either source or receiver sampling is sparse. Additionally, typical survey design does not account for the long offsets that are required if processing is to use diving waves in FWI for determination of the velocity field. The data that conventional processing discards at very long offsets now becomes critical for FWI, but sampling for these diving waves at long offsets does not require the same sampling interval as typically determined for conventional processing. These changes in criteria challenge some of the fundamental survey design metrics for conventional processing, but allow survey geometries that are very different from a 3D survey that is designed for conventional processing and imaging.

A second aspect of FWI that is critical for survey design consideration is the fact that FWI imaging uses the full wavefield for imaging. When a full visco-elasitic FWI (process includes inversion for Q) is implemented this includes all the multiples. It can be challenging to evaluate the coverage produced in the shallow section (or at the water bottom itself) when all multiples are included, but the water-bottom multiples can be used as a tool for survey design. This approach leverages the fact that FWI benefits from incorporating all available wavefield energy, but limits the evaluation to only the simple water layer multiples (excluding interbed and pegleg multiples), to yield better understanding of the minimum imaging improvement.

This meeting is organised by the Geophysics SIG committee.