从VSP资料求取速度参数的方法

AN APPROACH OF DETERMINING VELOCITY PARAMETER FROM VSP DATA

胜利油田计算中心

Computer Centre, Shengli Oilfield

本文着重讨论从VSP资料求取各种速度参数和提高计算精度的方法。初至波时间拾取是VSP速度分析的重要步骤,采用零交叉点拾取法对提高层速度计算精度有良好效果。“似层状介质”模型更接近地下实际情况,在此基础上根据走时反演原理用射线追踪和迭代算法,可以求得准确的层速度。文中研究了用VSP资料直接求取连续介质初始速度和速度梯度的方法。

The subject matter of this paper lays stress on the approaches to determine various velocity parameters from VSP data and improve the evaluation accuracy. First Break picking is considered a significant move for making VSP velocity analysis and it has produced a positive result in enhancing the evaluation accuracy of interval velocity by using zero ?crossing method. The quasi-layered medium model is almost identical to the actual situation. Based on which as well as travel time inversion theorem, the correct interval velocity expected could be obtained using ray-tracing scheme and iterative algorithm. Also, the approach to determine the initial velocity in continuous media and velocity gradient using VSP data is reviewed.