Integrated Seismic and Non-seismic Modelling for Crustal Type, Volcanic Risk Mapping and Generating a Common Earth Model

For sub-salt modelling offshore, a combined seismic and non-seismic approach can help reduce uncertainty for deeper structures such as volcanics and crustal geometry/type. Due to the presence of thick and complex salt in the area, the seismic imaging is sub-optimal, and therefore gravity and magnetics modelling is required to de-risk the interpretation, especially for the pre-salt sediment fill and for crustal thickness and type. All these factors play a prominent role in hydrocarbon prospectively in the region. The work presented here was first calibrated on one regional 2D seismic line from offshore Uruguay and the interpretation techniques extended to seven regional 2D seismic lines offshore Brazil. Using seismic interpretation along with gravity and magnetic modelling with relative weight applied on one or another depending on the quality of the data in the area resulted in an integrated earth model and mapping of volcanic structures.

The clear SDR’s signature from offshore Uruguay enabled regional mapping of these structures offshore Brazil in areas that are unclear in the seismic data alone. In addition, using this approach, exhumed mantle and volcanic intrusions in the crusts could also be mapped offshore Brazil which will help during hydrocarbon exploration in the area.