VELOCITY ANALYSIS IN THE p—x‐PLANE FROM A SLANT STACK WAVEFIELD*

Classical methods of interpretation of reflection seismic data are such that interpretation and processing usually occur in the “collected” frame of reference. However, in recent times other data planes have gained increasing acceptance in seismology as a viable alternative. Through linear transformations applied to a record section, both the t—p‐ and p—x‐planes can be produced. The r—p‐domain may be obtained from the t—x‐plane by a transformation known as slant stacking. Normal practice has been to do most of the data processing in the t—x‐plane and then transforming to the r—p‐plane. However, many of the procedures used in the t—x‐domain can be modified for use in the t—p‐plane to increase the coherence.

Velocity inversion may be carried out either in the r—p‐domain or further transformed to the p—x‐plane where the modified Herglotz‐Wiechert inversion may be applied. To perform the inversion, the t—p‐wavefield is converted to a p—x‐representation by the use of a new linear transformation technique, the cross‐stack. By a simple sampling process along a particular p—x‐trajectory, the Herglotz‐Wiechert method can be used to reconstruct an acceptable velocity model of the subsurface. A comparison of derived velocity structures is made between that produced by the Herglotz‐Wiechert technique and that of the Dix method.