Coherency analysis of polarity reversed diffracted wavefields using local semblance

• Published in: Geophysical Prospecting Vol. 70; no. 8; pp. 1327 - 1337
• Main Authors: Hosseini, Mohammad, Khoshnavaz, M. Javad, Siahkoohi, Hamid Reza
• Format: Journal Article
• Language: English
• Published: Houten Wiley Subscription Services, Inc 01.10.2022
• Subjects: Analysis; Diffraction; Diffraction imaging; Fault detection; Fracture zones; Image resolution; Imaging techniques; Local semblance; Polarity reversals; White noise; Workflow
• ISSN: 0016-8025; 1365-2478
• DOI: 10.1111/1365-2478.13240

ABSTRACT Diffractions carry out important information about subsurface features. These features include small‐scale objects, fracture zones and faults. There have been several robust pre‐ and post‐stack diffraction imaging workflows in the literature to attribute diffraction locations and properties. Most of the traditional workflows are not fully capable of dealing with polarity reversals in the case of polarity reversed diffracted wavefields. This challenge causes null measures at the location of such diffractions. To overcome this issue, which is an ongoing subject of research, we propose to implement local semblance analysis along moveout curves. To do so, the global scanning window is subdivided into smaller windows followed by semblance analysis over each window. The final coherency measure in each image point is computed by averaging the semblance measures from all the subdivided windows. We demonstrated the proposed workflow on synthetic as well as field recorded datasets in the post‐stack domain. The results prove the capability of the proposed method in circumventing polarity reversals without any need to conduct polarity correction prior to imaging. At the end, we studied the seismic imaging resolution in the presence of white noise through the proposed approach.