Pierre Hugonnet

De‐aliased, high‐resolution radon transforms

Multiple elimination methods based on the move-out discrimination between primaries and multiples rely heavily on the focusing of seismic events in the parabolic Radon domain. This focusing, however, is affected both by the finite spatial aperture and sampling of the data. As a consequence of the resulting smearing, multiple energy may be mapped into the primary model and conversely primary energy may be mapped into the multiple model. This leads to poor multiple removal and to the nonpreservation of the primary amplitudes. To overcome these pitfalls one has to make use of De-aliased, HighResolution Radon transforms. High-resolution Radon transforms have already been proposed by some authors. Here we present a novel approach that simultaneously tackles the aliasing and resolution issues in a non-iterative way.

High Resolution 3D parabolic Radon filtering

Summary 2D parabolic Radon filtering is a widely used method for multiple attenuation. However, for dense and wide-azimuth gathers that exhibit azimuthal variation effects, this approach can fail. Because of the variation of the curvature of the events with the azimuth, the bin gathers can not be processed in one go but must rather be split into sub-collections where the azimuth either has little variation or varies smoothly. We instead propose herein to take into account the azimuthal effects by incorporating an elliptical model for the variations of the curvature with the azimuth, and hence define a 3D parabolic Radon filtering. This is a more natural way of processing dense wide-azimuth gathers, by honoring their actual 3D geometry, which results in more consistent decompositions and in a better filtering.

Wavefield separation in borehole seismic by linear radon decomposition

2D and 3D borehole seismic profiling can provide with very valuable information for hydrocarbon reservoir appraisal : precise imaging of fault location, AVO estimation for petrophysical model validation at seismic scale. In order to get correct results 2D and 3D borehole seismic data need to be pre-processed with a special attention for wavefield separation. If there are a lot of efficient methods to tackle with this problem for zero-offset and offset VSP acquisitions, strong difficulties may arise when achieving wavefield separation on walkaway VSP’s datasets due to the very small number of receiver locations (5 levels is usual).

Wide‐azimuth techniques for processing high density 3D OBC data

High density wide-azimuth Ocean Bottom Cable acquisitions have proven their efficiency to better image complex structures in the North Sea. Yet conventional preprocessing sequences have not taken into account the full potential offered by such acquisitions (Boelle et al. 2008). In this paper, we present the advantages of a true wideazimuthal pre-processing regarding noise attenuation, PZ summation in the 3D τ-px-py domain, following Soudani et al. (2006), and multiple attenuation in the 3D τ-qx-qy parabolic radon domain as proposed by Hugonnet et al. (2008). The wide-azimuthal information can also be used to build the velocity model following a multi-azimuth strategy. The wide azimuth processing results are compared to more conventional processing approaches in a real case study.