公开(公告)号：US20030074140A1

公开(公告)日：2003-04-17

申请号：US09981226

申请日：2001-10-17

Applicant: WesternGeco L.L.C.

Inventor： Scott MacKay

IPC: G01V001/28

CPC classification number: G01V1/38 ,  G01V1/362 ,  G01V2210/52

Abstract: This invention removes the effects of variable water velocity by calculating and applying corrections that map the seismic data to an ideal case of constant water velocity. All of the corrections assume, from a separate analysis step, that the vertical (zero-offset) timing errors induced by the water-velocity variations and that the zero-offset water bottom times are available. Equivalently, the water velocities are assumed known. The timing errors and water velocities are related. The zero-offset water-bottom times are also assumed available. From this information, and an arbitrarily-defined nullidealnull water velocity, it is possible to calculate an observed (actual) water velocity relative to the nullidealnull case. The only additional information needed is the angle of the ray path through the water layer. The angle may be calculated directly from normal moveout velocities derived from conventional analysis of the seismic data, and the information above. A time-dependent and offset-dependent correction may be derived for each sample of the seismic data prior to normal moveout correction.

Abstract translation: 本发明通过计算和应用将地震数据映射到恒定水速的理想情况的校正来消除可变水速的影响。 所有的修正都是从单独的分析步骤假设水流速度变化引起的垂直（零偏移）定时误差以及零偏移水底时间是可用的。 同样地，水速度被认为是已知的。 定时误差和水位相关。 零偏移水底时间也假设可用。 根据该信息和任意定义的“理想”水速度，可以计算相对于“理想”情况的观测（实际）水速度。 所需的唯一附加信息是通过水层的射线路径的角度。 角度可以直接从从地震数据的常规分析得到的正常移动速度以及上述信息来计算。 对于正常移动校正之前的地震数据的每个采样，可以导出时间依赖和偏移相关的校正。