Optimising an Acquisition Design for Sub-salt Targets Using Full Wave Modelling

This paper comes to show the advantages of using Full-wave modelling in a complex geology where classic ray-tracing modelling has its limits. A real case study for a field in West Africa is presented, where full-wave modelling was used during the feasibility study to design and optimise Wide Azimuth marine acquisition.

The feasibility study covered complex model building and the investigation of different acquisition geometries from narrow azimuth to bi-wide azimuth designs. The effect of other acquisition parameters such as sail line interval and acquisition direction have also been investigated.

The results obtained showed a real advantage of using full-wave modelling during feasibility studies for complex geological structures. In the case study presented full wave study allowed to significantly reduce acquisition cost by selecting a sparse bi- wide azimuth compared to a denser wide azimuth for the same data quality. The final data obtained is suitable to remarkably reduce uncertainties related to sub-salt environment. The full wave study permitted to predict the image uplift obtained on real data with the proposed design.