In order to better apply the seismic wave prestack reverse-time migration technology,we studied the impulse
response of reverse-time migration.Starting from the impulse response of layered media model with offset,firstly,we
discuss the genesis of low-frequency reverse-time noise of the conventional correlation reverse-time imaging
conditions,analyze the advantages of the reverse-time migration conditions in up-going and down-going wavefield
separation for suppressing low-frequency noise,and compare the impulse responses in the above two reverse-time
migration conditions with smoothed migration velocity.Then,we analyze the influence of seismic wave numerical
dispersion on the accuracy of the reverse-time migration impulse response under the conditions of different
migration grid parameters and velocity distribution.The computational results show that the reverse-time
background noise is mainly caused by the up-going reflection wavefield corresponding to the relative wave
impedance difference interface during wavefield continuation.Velocity smooth can effectively reduce low-frequency
background noise while decrease the accuracy of imaging.Seismic wave numerical dispersion is one of the
important factors affecting the accuracy of reverse-time migration,and the selection of reserve-time migration
parameters must be extremely obey the numerical dispersion relationship.Meanwhile,model testing proves the
interchangeability of source and receiving point in reserve-time migration,which provides method guide for
reserve-time migration.By optimizing reserve-time migration parameters,application on actual land data obtains
good imaging result.
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