GOMCRUST - The crustal-scale extension of the 2004 BP velocity model for long-offset OBN acquisition setting

Summary We present an extension of the 2004 BP velocity model which is suitable for the assessment of cutting-edge seismic imaging methods as FWI applied to ultra long-offset ocean-bottom node (OBN) acquisitions. The 2004 BP model is routinely utilized to benchmark various velocity-model building approaches - in particular those developed to tackle the challenges encountered in geological settings comprising salt structures. Those challenges are typically related to the correct reconstruction of the subsalt structures or the sharp velocity contrasts between the salt bodies and the surrounding sediments. To make this model suitable for testing the emerging long-offset OBN acquisitions, we embed the original 2004 BP model within a crustal-scale velocity model inspired by the structural interpretation of the tomographic results from the GUMBO experiment (Gulf of Mexico). The resulting model allows for wavefield propagation within the rifted continental crust and the upper mantle and therefore for the undershooting of the salt and subsalt structures. Consequently, there is no need for extrapolation of the original BP model boundaries or resizing/resampling of its spatial dimensions. The GOMCRUST can therefore be seen as a geologically consistent evolution of the 2004 BP model, which allows to benchmark various seismic imaging workflow with long-offset OBN surveys.