What is the Benefit of Using Prestack Attributes

By

 Charles Bertrand¹, Thierry Tonellot², Frederique Fournier²

(1) Beicip Franlab, Rueil Malmaison, France (2) Institut Francais du Petrole, Rueil Malmaison, France

 It is becoming coming common practice to perform 3-D prestack inversion of iso-offset or iso-angles cubes, in order to estimate elastic parameters such as P- and S- impedances at the reservoir level. In particular , S- attributes should provide information on the reservoir parameters complementary to the information derived from P-attributes.

In the context of prestack attributes, four question arise. (1) What is the amount of non redundant information provided by the S- attributes ? (2) What are the best parameters (such as impedances and Lame parameters) for interpreting prestack attributes in terms of reservoir properties ? (3) How to define reservoir properties that are significantly related to the P- or S- information ? (4) What is the impact of the limited bandwidth of the prestack seismic attributes on the reservoir property estimation ?

These questions will be examined in this presentation through a deep-water case study. A general workflow has been proposed to quantitatively exploit the pertinent prestack attributes in relation to the reservoir properties, while assessing the uncertainties of such an interpretation. The workflow involved segmentation algorithms and estimation techniques in a probabilistic frame. It allowed for the derivation of maps or cubes of average reservoir properties, such as porosity or shale volume, and their associated uncertainties. It was an efficient tool for quantifying the benefits of prestack attributes.