Facies analysis from pre‐stack inversion results in a deep offshore turbidite environment

Abstract

In a companion paper (Nivlet et al.,2005), we have described an application of seismic pre‐stack inversion to retrieve acoustic and shear impedance models in Girassol field. The next step, which will be discussed in this paper, is the lithoseismic interpretation of the inversion results. Traditional seismic facies analysis consists in extracting various amplitude maps of a reservoir level, and producing probabilistic or deterministic seismic facies maps. In this paper, we will present a workflow reaching beyond this traditional approach, by producing a 3D geological facies proportion model, which can then be used as a direct constraint to high resolution geological modeling techniques. The workflow consists of 5 main steps: • well log interpretation calibrated on core data; • upscaling of the facies database at the seismic scale; • choice of appropriate seismic attributes to discriminate betweenn the different facies, compensating for instance for the shale compaction with depth; • probabilistic seismic facies analysis from the chosen seismic attribute cubes supervised by upscaled well information; • post‐interpretation of seismic facies analysis results in terms of mean proportions of geological facies; • consistency check between the facies model and seismic impedances.