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INTRODUCTION

Moveout differences between primary and multiple events are often used to discriminate primary and multiple energy in a CMP gather. Examples of methods which rely on moveout differences are NMO stacking and velocity transforms. NMO stacking can reduce multiple energy but is undesirable because the gathers cannot be reconstructed from the stacked traces. Velocity transforms, on the other hand, are invertible. An invertible transform allow gathers to be transformed from prestack space into velocity space and then back to the prestack space. Also, velocity transforms map primary and multiple energy into two distinct regions of model space. This allows the multiple energy to be separated from the primary energy with a simple masking procedure. Beam stack transforms, like the velocity transform, are invertible and map primary and multiple energy from the gather space into two distinct regions of model spaceBiondi (1990). Because of these two properties, the beam stacked space is a good space to identify and remove multiple energy. The beam stacking operator has additional advantages over velocity transforms. Unlike the velocity transform, beam stack transforms do not assume a global shape for events or constant amplitude across the event. Beam stack transforms simply model the stepout of events while velocity transforms model hyperbolic or near hyperbolic events. Because of this, beam stacking transforms are more appropriate than velocity transforms for the task of modeling data with non-hyperbolic moveout and AVO.
previous up next print clean
Next: MULTIPLE SEPARATION THEORY Up: Holden & Biondi: Multiple Previous: Holden & Biondi: Multiple
Stanford Exploration Project
11/11/1997