Common‐reflection‐surface stack and conflicting dips

Abstract

The recently introduced common-reflection-surface (CRS) stack simulates a zero-offset (ZO) section from multi-coverage seismic reflection data for 2-D media in a data-driven way, i. e., without explicit knowledge of the macro-velocity model. The "best" stacking operators are determined by an optimization of the coherency along different test stacking operators in the multi-coverage data. Previous implementations determine only one optimum stacking operator for each ZO sample to be simulated. Consequently, conflicting dips are not taken into account but only the most prominent event contributes to a particular stack sample. This can lead to a lack of coherency of some events in the simulated ZO section. In this work, I show how this limitation can be overcome.The pragmatic search strategy of the original CRS stack implementation consists of three one-parametric search steps to determine the stacking operators. In the first step, an automatic CMP stack, conflicting dips can hardly be considered because the respective stacking velocities might be quite similar. However, I observe that conflicting dips can still be detected and separated in the subsequent search steps that are applied to the result of the automatic CMP stack.I propose an extension of the pragmatic approach to account for conflicting dips. For ZO samples where conflicting dips are detected, an additional one-parametric search is required. This provides a set of three kinematic wavefield attributes for each of the conflicting events. Stacking along the respective operator for each particular event allows to simulate their interference in the simulated ZO section by means of superposition.