关键词: 速度误差, 深度误差, 叠前偏移, 叠后偏移, 偏移假象

Abstract:

Depth error in depth migration profile isn't equal to velocity error, sometimes it is twice as many as velocity error. To analyze the pseudo phenomena caused by migration velocity error, the authors of the paper study the depth error between poststack migration and prestack migration caused by same velocity error, and it is the depth error of migration profile is only related to velocity error and there is not direct relation with methods of depth migration (poststack migration or prestack migration). Then the numerical simulation of a complex lenticular body model with waveequation modeling and migration is done, and it is pointed out that the velocity error could not only induce depth error, but also change the modality of construction and the deformation in phase axis in subjacent layers. Furthermore, it could change the frequency of reflective event. They are the pseudo phenomena caused by migration. To correctly identify them is very important for testing the correctness of velocity model and seismic data explanation.

Key words: velocity error, depth error, prestack migration, post stack migration, migration pseudo phenomenon