Abstract：Based on geologic model, the paper studied the influence of random and regular noises on the precision of interval velocity estimation in prestack depth migration. The results showed that the random and regular noises have consistent influence regularity on the precision of interval velocity estimation, which is characteristic of stage, limit signal-to-noise (S/N) ratio. The velocity error is minor, tends to stable and has small influence on the velocity precision when the S/N ratio is greater than limit value; on the contrary, the velocity error increased rapidly and seriously affects the velocity precision when the S/N ratio is inferior to the limit value. In comparison with same level's random noises, the regular noises produce more serious influence and have higher limit S/N ratio. On that bases, the paper further analyzed the influence of static moveout on limit S/N ratio.The results showed that for random noises,the static moveout of 1.5 times of sampling time may seriously affect the estimated precision of interval velocity,which may significantly raise the limit S/N ratio.So,it should carry out seismic signal consistency processing, prestack noise attenuation and reducing static moveout in prestack depth migration processing of practical seismic data, and only doing so may we improve the precision of the prestack depth migration velocity model.
