Angle-domain common-image gathers in generalized coordinates

Angle-domain common-image gathers in generalized coordinates

Jeff Shragge

Abstract:

The theory of angle-domain common-image gathers (ADCIGs) is extended to migrations performed in generalized 2D coordinate systems. I develop an expression linking the definition of reflection opening angle to various generalized geometric factors. I demonstrate that generalized coordinate ADCIGs can be calculated directly using Fourier-based offset-to-angle approaches for coordinate systems satisfying the Cauchy-Riemann differentiability criteria. The canonical examples of tilted Cartesian, polar, and elliptic coordinates are used to illustrate the ADCIG theory. I compare analytically and numerically generated image volumes for a set of elliptically shaped reflectors. Experiments with a synthetic data set illustrate that elliptic-coordinate ADCIGs better-resolve the reflection opening angles of steeply dipping structure, relative to conventional Cartesian image volumes, due to improved large-angle propagation and enhanced sensitivity to steep structural dips afforded by coordinate system transformations.

Angle-domain common-image gathers in generalized coordinates