Demigration

At the stage of seismic data processing, an important role is played by the possibility of obtaining of so-called "benchmark seismograms", the main property of which is the maximum proximity to the ideal response of the medium on the reflected P-waves. I.e., these seismograms should present a useful signal of reflected waves, and all the amplitude-frequency characteristics, as well as the kinematic characteristics of the wave field should maximally match the field characteristics of the processed data.

In the procedure of processing there are various tasks that require such benchmark fields, moreover, depending on the task, the requirements to the quality of these fields may be different. These are, for example, tasks of static corrections calculation, verification of linear/nonlinear kinematic filtering procedures (for undistorted useful signal), compensation of distortions of amplitude-frequency characteristics of migration operator, caused by narrow data azimuthality, or insufficient discreteness of observation system when forming amplitudes at high frequencies, and other tasks.

The problem of demigration is solved by using specialized parameters of the BI-WFT 3D Cluster plugin. This is a particular case of applying the Kirchhoff migration operator reversal technique.

As the parameters in order to describe the response of the medium to the input impulse in the general case of demigration one may use:

1. elastic parameters of the reservoir Velocity-Depth Model (for modeling of both P-P and P-S waves);

2. grid model represented by seismic cubes Vp, Vs, Rho (for modeling of both P-P and P-S waves);

3. intercept/Gradient seismic parameter cubes (for modeling of P-P waves).

The kinematic parameters of the medium are described by the used classes of reservoir Velocity-Depth Model. The most important in terms of processing problems is the case of the use of the pre-migration image cube as the response of the medium. The obtained seismograms on the initial geometry of the observation system currently allow to solve such problems as:

1. task of static corrections adjustment;

2. creation of benchmark GIP gathers to compensate the geometry of the observation system. It is important to note that this task is actual even if the preliminary data regularization has been executed;

3. correct reconstruction of the correspondence scheme for each depth point of the offset - Angle of Dip/Reflection based on the use of an additional technology of attribute migration;

(please find theses of the report "Attributive Migration. New Opportunities for Migration Transformations" at the GeoEurasia-2018 conference or the abstract of the paper "Migration Transformations Capabilities for Wavefield Attribute Estimation" at the Geomodel-2018 conference)

4. additional technologies of the use of 'demigrated' gathers, considered as a reference model of the useful signal, are being developed.