Method for detecting earth formation fractures by seismic imaging of diffractors
View Patent ↗A method is disclosed for seismic imaging of subsurface diffractors. The method includes performing migration velocity analysis on a seismic time record section and depth migrating the time section for offsets exceeding one-half a distance between a seismic energy source and a seismic receiver most distant from the source during acquisition of seismic data used to generate the time record section.
1. A method for seismic imaging of subsurface diffractors, comprising:
performing velocity analysis on a seismic time record section;
depth migrating the time section for offsets exceeding one-half a distance between a seismic energy source and a seismic receiver most distant from the source during acquisition of seismic data used to generate the time record section; and
determining a time gradient of the diffractors and attenuating spatial aliasing of specular reflective events in the depth migrated section using the time gradient.
2. The method of claim 1 wherein the depth migrating comprises Kirchoff migration.
3. A method for seismic imaging of subsurface diffractors, comprising:
deploying a seismic energy source at a selected position near the Earth's surface;
deploying a plurality of seismic receivers at selected positions along the Earth's surface;
actuating the source at selected times;
recording signals detected by the receivers;
performing velocity analysis on a seismic time record section made from the recorded signals;
depth migrating the time section for offsets exceeding one-half a distance between the source and one of the receivers most distant from the source; and
determining a time gradient of the diffractors and attenuating spatial aliasing of specular reflective events in the depth migrated section using the time gradient.
4. The method of claim 3 wherein the depth migrating comprises Kirchoff migration.
5. A computer program stored in a computer readable medium, the program having logic operable to cause a programmable computer to perform steps comprising:
performing velocity analysis on a seismic time record section;
depth migrating the time section for offsets exceeding one-half a distance between a seismic energy source and a seismic receiver most distant from the source during acquisition of seismic data used to generate the time record section; and
determining a time gradient of the diffractors and attenuating spatial aliasing of specular reflective events in the depth migrated section using the time gradient.
6. The computer program of claim 5 wherein the depth migrating comprises Kirchoff migration.