Organization and imaging of three-dimensional seismic reflection data before stack

Pre-stack imaging of 3D seismic reflection data is at present a major challenge of seismic data processing. The main difficulty arises because of the limited power of today's computers. Manipulating volumes of 3D multi-fold seismic data and, especially, executing the large number of mathematical operations required for 3D migration is presently a very complicated and time consuming task. More than that, 3D seismic reflection surveys are characterized by very irregular acquisition geometries. This requires special migration algorithms and even new thinking.; In this thesis we present a new approach to imaging 3D pre-stack seismic reflection data. It is a practical alternative to the full 3D pre-stack depth migration and takes special care of irregular acquisition patterns. The objective of the method is three fold: (a) to perform migration before stack, (b) to correct for three-dimensional seismic effects, (c) to provide a three-dimensional velocity model and a depth image.; A 3D processing scheme is presented here. It is composed of three procedures which are different approximations to the full 3D pre-stack migration operation. The interaction between those schemes is simple, and each procedure serves as a building block for the next module. That is due to the special derivation of the algorithms in the frequency domain. The three modules that compose this work are: (1) Reorganization of multi-fold data on a regular pre-stack grid, based on Dip-Moveout and the inverse transform (DMO{dollar}{bsol}sp{lcub}-1{rcub}{dollar}). (2) 3D pre-stack time migration, using the PSI technique. (3) Two-pass 3D pre-stack depth migration, performed by splitting the full 3D calculation into a succession of 2D operations.