2D Vp modeling of the Albian-Cenomanian section using geological constraints, 3D extrapolation, and GRV uncertainty analysis of Aptian presalt reservoir: A Santos Basin example Available to Purchase

Presalt reservoirs in the Santos Basin are the main O&G accumulations of Brazil. It is remarkable that the seismic data evolution regarding acquisition and processing, delivers the best possible earth model, reducing decision risks, and minimizing unnecessary costs in any stage of the fields. Vp modeling plays as a vital step for the seismic migration, influencing interpretation, depth forecasting, and rock property estimation. Currently, Vp models are built looking for geological confidence, incorporating the existing heterogeneities, allowing subsurface geological characterization enhancement, especially in geologically complex regions, such as the Brazilian Presalt province. Concerning the Santos Basin, the main heterogeneities to be considered is the representation of the Aptian evaporitic saline section, Albian-Cenomanian carbonatic/siliciclastic section, and intrusive and/or extrusive igneous rocks above the reservoirs. Although the Vp of the saline section are well known, only few studies attest the impact of Vp modeling related with the Albian-Cenomanian layers and igneous rocks. To understand the vertical and spatial behaviors of Vp in the Albian-Cenomanian layers, it was necessary to perform a geological characterization of this section, splitting it into proximal, intermediate, and distal sectors of the basin, through well analysis and seismic interpretations. Statistical analysis of the Vp and lithology logs have provided a better understanding of these variables, aiming in the parameters´ quantification to be used in the Vp modeling process. The results add valuable aspects for inherent impacts to the volumetric estimation of rocks. Unlike the Campos Basin, where the Albian-Cenomanian layers form thick rafts, which exert a great influence on the modeling of Vp, in the distal sector of the Santos Basin, location of the Presalt fields, this context is distinct. Apparently, the relevance of these layers is lower than the considerations for salt, however, when the salt thickness is thin, or in the presence of salt over-hangs, without this proposed geological consideration, the updating of Vp by conventional techniques can become unprecise and critical.