薄层干涉对叠加速度分析精度的影响

 在薄层发育区，无论是常规叠加速度分析，还是叠前时间偏移处理中的剩余速度估算，均应考虑薄层干涉响应对速度的影响。本文通过对薄层干涉现象的分析，指出薄层出现干涉的炮检距随着埋藏深度、地层平均速度、薄层厚度以及地震波的主频的变化而改变。地层厚度越小，出现干涉的炮检距越小；当地层厚度小于1/4波长时，无法分辨薄层顶、底界面的反射；地震波的主频越高，出现干涉的炮检距越大；地层厚度一定，地震波频率不变时，地层埋深越大，速度越高，出现干涉的炮检距越大。因此在实际的薄储层发育区的地震资料处理中，选择切除参数和炮检距范围时，应避免较大炮检距处干涉带来的影响，保证拾取速度的准确性。

Influence of thin-layers interference on precision of stack velocity analysis

In thin-layer development zone, either the common stack velocity analysis or residual velocity evaluation in prestack time migration processing should consider the influence of thin-layer interference response on velocity. By analysis of thin-layer interference phenomenon, the paper points out that the offsets appearing the thin-layer interference change with buried depths,average velocity of formation, thickness of thin layer and dominant frequencies of seismic waves. The thinner the thickness of formation, the smaller the offsets appearing the interference; the reflections from top and bottom interfaces of thin layer can not be identified when the thickness of formation is less than 1/4 wavelength; the higher the dominant frequency of seismic waves,the larger the offsets appearing interference;the deeper the buried depth of formation and higher the velocity, the larger the offsets appearing interference when the thickness of formation is certain and without change of frequency of seismic waves. Therefore, during the seismic data processing in practical thin reservoir development zones,we should avoid the influence resulted from interference at larger offsets when choosing mute parameters and offset range, ensuring the correctness of velocity pickup.