Imaging improvement by prestack signal enhancement

Abstract

ABSTRACTThe quality of recorded seismic data depends on many factors and a low signal‐to‐noise ratio leads to a low quality of processing and imaging. The zero‐offset common‐reflection‐surface stack and multifocusing methods have been successfully applied to improve the prestack signal‐to‐noise ratio by the partial summation of coherent seismic events. However, in the case of non‐hyperbolic traveltime behaviour of seismic events these approaches can result in non‐optimal partial summation.We develop a local common‐offset approximation for the traveltime stacking surface. It allows us to adequately approximate the traveltimes of reflection events in the vicinity of an arbitrary offset. Here, the stacking operator is interpreted as a local second‐order traveltime approximation of the seismic event and it is used for the purpose of partial summation. An algorithm and a numerical implementation scheme are discussed. The proposed signal enhancement procedure was applied to synthetic and real 3D data. Imaging results of the enhanced data show a high potential for reliable imaging in complex subsurface environments.