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Chapter 2: PS imaging operators

Chapter 2 presents a simple description of existing imaging operators for PS data. The first two operators are Normal Moveout and Dip Moveout. The problem of CCP stacking has been widely addressed in the past Iverson et al. (1989); Tessmer and Behle (1988). The solutions presented in these works apply a lateral shift to the traces in the CMP gathers, such that the new trace position corresponds with the lateral position of the conversion point. However, the final representation of the results is in the data domain, which is composed of time, data midpoint location, and surface offset.

The last imaging operator that I describe is prestack depth migration. An ideal case would be to use a two-way wave-propagation operator, such as reverse-time migration or elastic wave-equation migration. These processes are very expensive and not yet practical for most data sizes. As an approximation to this process, I present an acoustic prestack wave-equation-based migration operator, using two propagation velocities, a P-velocity to propagate the source function and an S-velocity to propagate the receiver function. This approximation is valid, since the source for an OBS acquisition is acoustic, and I use the approximation that the elastic components of the seismic wavefield are produced at the reflections.

Chapter 2 describes the basic problems for imaging PS data. I conclude that the ideal domain to address most of the problems for PS imaging, is composed of depth, image-midpoint location, and subsurface offset.


next up previous print clean
Next: Chapter 3: PS angle-domain Up: Thesis Overview Previous: Thesis Overview
Stanford Exploration Project
12/14/2006