A method for determining migration before summation including recording seismic reflection traces, for constituting a collection of traces to be migrated before summation and without weight correction. The traces being classified according to a given criterion and using a velocity model. The method including determining, for each point of interest M in a domain (X, Z), at least one line of slope determined on the basis of a line of slope map, in determining the specular rays associated with one point M and for the line of slope, and in computing the time and amplitude characteristics of each of the specular rays for deducing therefrom the reflection factor in each point M.
Method for solving the classical inversion problem of finding the angle dependent reflection coefficients along selected reflectors in the subsurface. The input data to the method include seismic constant offset or constant angle data cubes from Pre-Stack Depth Migration of Kirchhoff type and the corresponding reflectors and velocities from the interpretation and velocity analysis of the data. One or more of the reflectors are chosen and ray modeling is done to create synthetic seismics for all shot/receiver pairs in the seismic survey. Based on these modeling results, amplitude correction maps are made for the various reflection angles. These correction maps are applied to the amplitudes from the seismic data. The corrected amplitudes are approximations to the angle-dependent reflection coefficients in all points on each selected reflector. For each point, a weight function is computed, giving the quantitative resolution of the estimate of the reflection coefficient.
Method of determining the specular source/receiver pairs associated with seismic images produced from a transformation of multi-offset seismic wave records as a function of time in the depth domain.When using a prestack depth migration algorithm of Kirchhoff type, one also calculates and saves, in addition to the necessary traveltimes of the rays from the sources and receivers of the acquisition device to the image points of the image to be migrated, the line parameters of these rays and the desired quantities to be reached in fine. Then, once the prestack migrated volume produced, the local slopes of seismic events of interest for the image points considered are extracted. Comparison between line parameters saved during migration and the normal to the local slopes at the image points considered shows which ray is specular among those for which information has been saved, and allows to produce then the required quantity, which is then referred to as specular quantity.Application: subsoil seismic imaging for example.
A method and apparatus for compensating acquired seismic data for the presence of dipping events are disclosed. The method includes migrating the acquired, unstacked seismic data; and spatially mapping the migrated seismic data to correct their respective offsets while maintaining the angle of incidence to a dipping event. The method may be performed by a programmed computing device or encoded as instructions for a computing device on a program storage medium.
