2.5D Multi-Focusing Imaging of Crooked-Line Seismic Surveys

Abstract

Summary Due to logistical and environmental restrictions, seismic data are often acquired with a 2D crooked-line geometry. The crookedness of profiles, irregular topography, and complex subsurface geology with steeply dipping and curved interfaces could negatively affect the signal-to-noise ratio of the data. Crooked-line geometry violates the assumption of a straight survey line that is a basic principle behind the 2D Multi-focusing (MF) method. Irregular survey geometry leads to the cross-profile spread of midpoints in the vicinity of the processing line. In this research, we have developed a novel Multi-focusing algorithm for crooked-line seismic data and revisited its travel-time equation to achieve better signal alignment before stacking. We present a 2.5D Multi-focusing reflection travel-time expression which explicitly takes into account the midpoint dispersion and cross-dip effects. The new formulation corrects normal, in-line, and cross-line dip moveouts simultaneously. The 2.5D Multi-focusing method can perform automatically with a semblance based global optimization search on the real data. We investigated the accuracy of the new formulation by testing on different synthetic models. Numerical tests show that the new formula can focus the primary reflections with good precision at their right location, remove anomalous dip-dependent velocities, and extract true dips from seismic data for structural interpretation.