Adaptive estimation of the upgoing wavefield from a variable-depth recording in the case of a dynamic sea surface

Abstract

The estimation of the upgoing wavefield based on a ghost model is well-known as receiver deghosting. The shape of the rough and dynamic (time-varying) sea surface and the varying receiver depth should be included to carry out this step correctly. However, the exact shape of the dynamic sea surface is not commonly measured. Therefore, the ghost model is often inaccurate, introducing artifacts in the deghosted result. We have developed a data-driven, iterative, receiver deghosting method that includes the estimation of the dynamic shape of the sea surface and the varying receiver depth. The deghosting algorithm is based on, respectively, wavefield propagation from the varying receiver level up to the dynamic sea surface and wavefield propagation from the dynamic sea surface down to the varying receiver level. The depth of the receivers relative to the height of the dynamic sea surface is estimated and updated at each iteration. We validate the deghosting method on 2D simulated data recorded on a variable depth and 2D simulated data recorded with a dynamic sea surface. Our deghosting method gives a significant uplift on the simulated data given that the initial ghost model is inaccurate. On the field data, recorded with a midwater, quasistationary cable, our deghosting method is able to correct the receiver depth and provides an accurate deghosting result. The performance of the deghosting method is similar to the performance of a multicomponent decomposition method in this realistic scenario.