Phase Space Migration  a Fast Migration Algorithm for Densely Sampled Data
Abstract
We present a migration method in the coupled rayparameter domain that is fast and efficient for seismic data that are densely sampled in the sourcereceiver configuation space. The method is based on slant stacking over both shot positions and offsets for all the recorded data. If the data acquisition geometry permits, both inline and crossline source positions and offsets can be incorporated into a multidimensional phase velocity space which is regular even for randomly positioned input data. By noting the maximum time dips that are present in the shot gathers and constant offset sections, the number of plane waves required can be estimated and this generally results in a data reduction of at least one and possible two orders of magnitude. The required travel time computations for depth imaging are independent for each particular plane wave component and thus can be used for either the source or the receiver plane waves during extrapolation in phase space, reducing considerably the computational burden. Even so, each source and receiver plane wave component must be combined with all other receiver and source components for a complete diffraction summation. Since only vertical delay times are required, many travel time techniques can be employed and the problems with multipathing and first arrivals are either reduced or eliminated. Further, the shot plane wave integral can be pruned to concentrate the image on selected targets. In this way the computation time can be further reduced and the technique lends itself naturally to a velocity modelling scheme where for example, horizontal and then steeply dipping events are gradually introduced into the analysis. Of course this imaging scheme can be implemented in parallel using a distributed architecture like a PC cluster to compute various plane wave sections since they are independent of each other. The common rayparameter image gathers can be used exactly like common angle image gathers for residual migration velocity analysis. The migration method lends itself to imaging in anistropic media since phase space is the natural domain for analysis.
 Publication:

AGU Spring Meeting Abstracts
 Pub Date:
 May 2005
 Bibcode:
 2005AGUSM.S41B..07S
 Keywords:

 7260 Theory and modeling;
 7294 Instruments and techniques