Multicomponent Seismic Acquisition in the Arabic Gulf - Should we Take a New Look at the Acquisition Parameters

摘要

Sea Bottom Acquisition is standard procedure for seismic in a large part of the Arabian Gulf. Typically it has been done with 2-component recording (hydrophone and vertical geophone), 25 to 50 meter recording spacing and similar shot spacing which generally has given good P-wave information. Lately we have seen the introduction of 4-component recording (4C), hydrophone and 3-component geophones. We have, however, not seen many examples of useful data being extracted from the addition of the two horizontal components. Typical for the region is shallow water and a very high seismic velocity just below the sea bottom. This has a very dominating effect on wave propagation and penetration. It gives rise to very strong P-wave multiples. Using full elastic modelling we also find strong wave mode conversion to S-waves near the surface. We thus expect to see reflected S-waves in 4C data. Modeling results demonstrate that they will be stronger at smaller offsets and with the typical acquisition procedure used today they will be aliased. These waves might have important lithological information, but we will need to acquire the data in a better way including reduced spacing and perform offset-dependent data processing.