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7th Middle East Geosciences Conference and Exhibition
Manama, Bahrain
March 27-29, 2006
1 TEEC, Burgwedeler Str. 89, Isernhagen, D-30916, Germany, phone: +49 (0)511 7240452,
[email protected]
2 Dept. of Applied Mathematics, LGC UNICAMP, C.P. 6065, Campinas, 13081-970, Brazil
3 LGC UNICAMP, Campinas, Brazil
4 TEEC, Burgwedelerstr. 89, Isernhagen HB, 30916, Germany
Multiple suppression generally relies on the filtering of multiples if their kinematic behaviour significantly deviates from the
traveltimes of primaries. Otherwise, multiple prediction and subtraction may be appropriate, using information either from a
subsurface model, or from seismic
data attributes. Such information is required in the case of land data, where high -velocity
rocks may be present up to the surface, leading to a similar kinematic behaviour of primary and multiple reflections. That
information is required in high accuracy and detail since the multiple generating interfaces cannot be assumed to be
perfectly flat and uniform, and moreover the multiples are further obscured by near-surface effects, i.e., velocity variations
and ground roll noise.
Very detailed information on the kinematic characteristics of seismic
data is provided by the Common-Reflection-Surface, or
CRS imaging technique. At each point of the image, this technique derives a locally adapted traveltime approximation. The
corresponding local imaging parameters, i.e., the CRS attributes, comprise surface related incidence angles and wavefront
curvatures that may well be used to identify and model multiple arrivals.
The multiple reflections can be identified by their behaviour in the CRS attribute
domains. For this task, three CRS attributes
are available from 2D data, and eight attributes from 3D data. The CRS traveltime approximation is then used to model the
multiple arrivals in the prestack data around the considered image location. Since the CRS traveltime approximation is valid
beyond the image CMP location where the multiple was identified, the multiple can be suppressed at the surrounding CMP
locations as well, without additional identification efforts.