3D seismic constraint definition in deep-offshore turbidite reservoir

Abstract

Girassol is a turbidite field located in deep offshore Angola. This field is particularly challenging in terms of reservoir characterization due to the high complexity of reservoir geology (channel-levees complexes eroding themselves partially). However, by integrating properly the high resolution 3D pre-stack seismic with well data, seismic velocities, stratigraphy and structural information, extraction of a quantitative 3D high resolution geological information becomes possible. The proposed workflow is divided into three parts: - pre-stack stratigraphic inversion, to estimate 3D acoustic and shear impedance model explaining optimally available seismic data: - probabilistic seismic facies analysis from the inversion results based on a discriminant analysis technique; - geological facies proportions computation from the previous step results by a novel approach developed to account for scale differences between seismic facies and detailed geological facies, in order to extract information at the geological scale, and infer the small heterogeneities. As a result, we obtain a set of 3D geological facies average proportion volumes, which can be used in a further step to better constrain geological modelling. Copyright © 2007, Institut français du pétrole.