The impact of heterogeneous salt velocity models on the gross rock volume estimation: an example from the Santos Basin pre-salt, Brazil

The thick and heterogeneous salt section in the Santos Basin, offshore Brazil, imposes great challenges to access the pre-salt hydrocarbon reservoirs, especially in relation to seismic imaging, signal quality, and depth positioning. Some problems arise from the current velocity models for the salt section, which for the majority, assume the salt is a homogeneous halite layer. In the Santos Basin, the commonly assumed salt - halite - only makes up to 80% of the mineral in this section. The inclusion of other salts as stratification in the velocity models, based on seismic attributes, has achieved good results in the last decade, especially for depth resolution. In this work, we analyze the benefits of different velocity models, considering presence/absence of salt stratification, and comparing the gross rock volume above the oil-water contact. The results show a significant effect on depth resolution of the events, as well as on volume estimation, indicating that more reliability captured by the complex velocity models will ensure the more confident the resulting volumetric information is.