Generalized-Screen Operators with a Spatially Variable Background Velocity

P241 GENERALIZED-SCREEN OPERATORS WITH A SPATIALLY VARIABLE BACKGROUND VELOCITY ROBERT J. FERGUSON 1 and GARY F. MARGRAVE 2 Abstract 1 For a recording aperture of dimensions M by N the cost of migration and modeling in heterogeneous media is proportional to MN [ M + N] . To reduce this cost we derive two efficient operators. One reduces the number of significant values in the extrapolation matrix by desampling the velocity field. The resulting cost is proportional to mnMN log 2 ( mn) where m and n are the dimensions of the desampled velocity field. The second operator restricts the