Patent ID: 6577955
Filing Date: 2003-06-10
Classification: G01V

Abstract:
A method of updating a subsoil velocity model, in which:a. implementing depth migration prior to data addition on a set of seismic traces acquired in register with said subsoil, the migration being implemented with the help of at least one starting velocity model and serving to determine one or more trace collections each describing the subsoil vertically below a point on the surface; b. picking one or more events which reflect vertically below the surface point under consideration on at least one collection of traces obtained using said migration; c. determining a reflector depth and dip for each picked event as well as a reflector dip in register with said surface point; and d. implementing ray tracing between said reflector and the surface to determine collections of sound source and receiver pairs, together with data characteristic of travel times and time gradients which correspond to the ray traces associated with said pairs; e. wherein subsequent processing is implemented in which the following steps are iterated: i. dynamically migrating travel time and time gradient data previously obtained with the help of parameterization of the velocity field; ii. characterizing the alignment of the migrated points obtained in this way; and iii. updating the parameterization; the processing selecting the velocity field parameterization which optimizes the alignment of said migrated points.