Publication Date:
2016-08-03
Description:
Velocity-model building with a good understanding of anisotropy is one of the important elements in a prestack depth migration (PSDM) project. During a recently conducted PSDM project, we observed that (1) the application of negative delta/epsilon is necessary to achieve reasonable depthing and gather flatness, and (2) azimuthal variation in gather flatness exists in the interval where negative delta/epsilon are necessary. A geologic explanation of these interesting observations was necessary to justify the velocity-model-building result. Investigation of stress magnitude/orientation and theoretical anisotropy of unconsolidated sandstone under nonhydrostatic stress revealed that these observations can be explained by stress-induced anisotropy. This concept may be applicable to other fields, and the existence of azimuthal anisotropy and value of anisotropy parameters can be roughly estimated by the method described.
Print ISSN:
1070-485X
Electronic ISSN:
1938-3789
Topics:
Geosciences
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