Hybrid target-oriented salt interpretation in the Gulf of Mexico

Abstract

The top-down method for salt interpretation starts with the search for salt-sediment interfaces, which begins at the shallowest depths and progressively moves deeper. This search is typically conducted on intermediate seismic products such as sediment flood, salt flood volumes, overhang sediment flood, and overhang salt flood depth migrations. However, with this approach, poorly imaged subsalt areas become known only after spending considerable time interpreting intermediate salt features. We evaluated a new method for streamlining this traditional approach to salt-model building wherein a reference salt geometry was obtained earlier in the salt interpretation process. Having a reference seismic volume helped to identify poorly imaged subsalt targets much sooner. A hybrid of model-based and data-based interpretations was then performed for the poorly imaged subsalt areas, whereby interpretation was completed by proposing geologically viable models that were continuously verified by their impact on geophysical (seismic) data. In poorly imaged areas, we looked bottom-up, rather than top-down, to establish a salt geometry that best fit the geologic model as well as the geophysical data. Our hybrid target-oriented approach is useful for not only reducing the interpretation cycle time but also for improving images beneath the salt.