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Introduction

In ray-based reflection tomography picking reflectors is an integral and painful part of the process Clapp (2001); Kosloff et al. (1996); Stork (1992); van Trier (1990). The general methodology is to pick a series of reflectors from a migrated image. A set of rays are then calculated that reflect at the picked interfaces. A major problem is the human intensive nature of reflector picking, especially for 3-D data. Automatic pickers can help, but significant human quality control (QC) is still necessary. A high level of QCing is required because inaccurate reflector picks lead to inaccurate reflector dip estimates, which in turn leads to back projecting information to the wrong portion of the model space, seriously hampering the inversion.

In this paper I present a method to eliminate, or at least significantly reduce, the need for reflector picking. I calculate a dip field and coherency from a migrated image by first using the plane-wave estimator from Claerbout (1992) and later used by Bednar (1997). I next refine the dip estimate using the methodology described in Fomel (2000). I then automatically select back projection points based on dip coherency and semblance strength. The method is applied to a 2-D North Sea Dataset. The turn around time is reduced significantly and the overall image quality is equal to or better than conventional reflector picking approach.


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Next: Theory Up: Clapp: Ray-based tomography with Previous: Clapp: Ray-based tomography with
Stanford Exploration Project
9/18/2001