Quantitative regularity analysis of offset-vector sampling for seismic acquisition geometry

Abstract

Symmetric acquisition geometry consisting of identical sampling of shots and receivers, can maintain the spatial continuity of the wavefield automatically, according to symmetric sampling theory. However, asymmetric geometry is often adopted in practical seismic exploration applications. Such geometry can cause uneven sampling and is necessary to be assessed for its sampling performance prior to acquisition. In conventional survey design, based on the common mid-point (CMP) analysis for a horizontally layered earth or common reflection point (CRP) analysis for a complex subsurface structure, the quality of acquisition geometry is generally judged by such bin properties as effective fold, offset scalar and azimuth distributions. However, these conventional approaches are limited by an incomplete understanding of the offset-vector sampling. Therefore, we propose a new method for quantitatively evaluating the continuity of offset-vector sampling including four spatial coordinates of shot and receiver. On the basis of physical potential energy and force-balance principle, it analyzes the regularity coefficient of offset-vector sampling as a whole using potential function model and takes into account fold, offset-scalar and azimuth distribution factors. The combination of regularity coefficients of every bin can produce spatial continuity distribution of offset-vector sampling. Similar to symmetric sampling, this approach emphasize the spatial relationships between adjacent bins rather than single bin attribute, since it aims to maintain the spatial continuity of the wavefield which allows the faithful reconstruction of the underlying continuous wavefield. Using this method, we can quantitatively compare spatial continuity distribution for different seismic acquisition geometries, and then choose the better acquisition scheme.