【摘要】 提出一种可对起伏地表采集的三维地震资料直接进行偏移成像的叠前时间偏移方法和流程.它用两个等效速度描述近地表和上覆层对地震波传播的影响,可对炮、检点不在同一水平面的三维地震资料直接进行叠前时间偏移处理.该方法不对近地表地震波传播做垂直出、入射假定,因此可适应高速层出露等不存在明显低、降速带情况.描述近地表和上覆层的两个等效速度参数可依据偏移道集的同相轴是否平直来确定,避免了确定近地表速度的困难;而对已知近地表速度的情况,则可进一步修正近地表速度,获得更好的成像效果.用三维起伏地表的理论数据和中国东部某工区实际数据验证了所发展方法和处理流程的有效性和实用性.更多还原

【Abstract】 We present a 3D prestack time migration scheme and workflow that can image land seismic data without datum static corrections.The scheme mimics the influences of the near-surface and overlay on wave propagation using two equivalent velocities.As a result,it is not necessary for wave path to be vertical incidence in the near-surface,as in conventional static corrections.This leads to the proposed scheme which can handle the more complex surface cases,such as the exposure of high velocity in the near-surface.The proposed scheme can update the two equivalent velocities with respect to the flats and consistency of the events.A synthetic 3D dataset and a field 3D dataset without datum static corrections are used to demonstrate the scheme and the workflow.更多还原