Application of Prestack Wide-Azimuth Coherence Technique in Complex Fault Area

Abstract

The Permian in the northwest of Sichuan Basin is buried deep (more than 6000 m), and a large number of small Fault Horst structures are developed. The fracture system is very well developed, which leads to multiple solutions of prediction results, and the effect of various prediction techniques is very poor. Using the characteristics that P-wave propagates in parallel or vertical fractures in anisotropic media, the properties of seismic reflection data are studied, and the seismic information is mined to guide the study of fracture development law. Based on the seismic data of “two widths and one height”, the prestack wide-azimuth coherent fracture prediction technology is studied. First of all, according to the post stack coherent attributes to find the general law of fault system development, then, the wide-azimuth data are divided into azimuth and angle. On the partial stack data volume with azimuth, the azimuth coherence volume is calculated by using the characteristics of seismic amplitude changing with azimuth, so as to predict the development characteristics of faults and fractures.

Prestack wide-azimuth coherence technique is more close to the actual geological phenomenon in describing the fault development zone and the morphological characteristics of fault and fracture cavity, which is helpful to the selection of drilling well location target. Compared with the conventional post stack coherence technology, it not only reduces the multi solution, but also can predict relatively small-scale fractures. At the same time, it has the anti-interference ability of post stack coherence, and has the characteristics of fast and efficient prediction, which is suitable for rapid and efficient exploration and development stage.