High Resolution, Super Efficient Wide Azimuth Beam Tomography for Velocity Model Building

Abstract

Abstract

We present a novel high resolution, wide azimuth Beam Tomography (BT) based on the Fast Beam Migration (FBM) algorithm. The Beam Tomography uses Fast Beam Migration to directly output a set of image points (x,y,z) with velocity update values, which bypasses the time consuming steps required for traditional tomography, including preparing the gathers for semblance analysis, semblance picking and back-projection picks QC. The method enables a very rapid estimation of the depth or time delays along each ray that can be used to produce a high quality alignment of the common-image angle or offset gathers. A 2000 sq km velocity model can be updated using 400 CPUs in less than 5 minutes. In addition, Beam Tomography output contains image point azimuth information and this allows the tomographic update to go beyond the current limitation of limited wide azimuth velocity updates. In summary, Beam Tomography allows for faster turnaround time for large 3-D seismic projects and at the same time increases the accuracy of the velocity model by using wide azimuth information that is typically unavailable in traditional tomography. In addition to single parameter update (one time delay or residual velocity value for each image point), multiple parameter update (time delays for each offset value), we now have a wide azimuth and offset update (time delays for each incidence-reflection angle pair, for each azimuth and offset).

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016