提高OBC覆盖次数计算精度的新方法

A new method for improving the computation accuracy of OBC bin fold

中国石油集团东方地球物理公司物探技术研究中心，河北涿州072751

Xu Yinpo,Technical Research Center of Geophysical Prospecting,BGP,Zhuozhou 072751,China

在海上OBC地震勘探中，OBC面元覆盖次数除了受目的层深度、速度的影响，还受到海水深度、速度等参数的影响。为此，运用Snell定律
建立了两层水平反射界面模型的OBC反射点坐标四次方程，严格地推导出与海水速度和深度、目的层速度和深度以及炮检距有关的反射点位置的
解析解，根据不同的实际情况确定了符合条件的解析表达式，给出了能适用于海水深度变化和目的层速度变化，提高OBC面元覆盖次数计算速度
和精度的新方法。模型试算和实际应用结果证明了该方法的有效性和必要性。

In marine seismic exploration,OBC bin fold is impacted by the depth and velocity of target layer,as well as the water depth
and velocity,etc. Therefore,on the basis of the Snell’s law,we derive a quartic equation of OBC reflection point coordination
of the model with two horizontal reflection interfaces. From the quartic equation,accurate solutions of the reflection point
are obtained and determined analytically based on the different actual conditions,expressed as a function of water
velocity,water depth,offset,underwater target depth and velocity at the reflection point. The new method is adaptive to the
variation of water depths and target-layer velocity and improves the calculation efficiency and accuracy of OBC bin fold.
Model test and actual data application proves the validity and necessity of the method.

10.3969/j.issn.1000-1441.2012.02.012