Depth-calibrating seismic data in the presence of allochthonous salt

Seismic depth errors can be significant in PSDM-processed seismic data. The purpose of this paper is to discuss best practice techniques for depth-calibrating seismic volumes, particularly in the presence of allochthonous salt where lateral and vertical velocity heterogeneity is great. We will present the concepts of apparent seismic depth and true seismic depth, propose anisotropy as a first-order mechanism for seismic depth error, discuss the implications of depth error as it pertains to well planning and resource estimation, and present different corrective measures and discuss their implementation. Our paper will be supported by two case studies, one from the deepwater Gulf of Mexico and another from offshore West Africa.