基于正态分布权函数的VSP-CDP叠加成像

基于偏移理论的成像技术受观测系统限制，导致成像剖面边缘的“画弧”现象严重，基于射线追踪的VSP-CDP叠加成像方法可实现VSP保幅成像，但是面对复杂构造时难以获得准确的成像和速度模型。为此，基于动态射线追踪有效邻域波场近似理论，提出了一种非零井源距VSP资料叠加成像方法。通过研究正态分布的性质及特点，推导了基于正态分布叠加的权函数计算公式，并用于VSP叠加成像，将深度—时间域的每一个采样点转换成反射点井源距—深度域的多个样点，使反射点的覆盖次数均匀。模型试算及实际资料处理结果表明，基于正态分布权函数的VSP-CDP叠加成像方法提高了成像精度。

VSP-CDP stack imaging based on the weight function of normal distribution

Limited by the geometry,the imaging sections based on migration imaging technique have serious "arc phenomenon" at the edge.VSP-CDP stack imaging method based on ray tracing can realize amplitude-preserved VSP imaging.However,it is difficult to obtain accurate structural imaging and velocity model in complex structure situation.Therefore,a non-zero-offset VSP stack imaging method was proposed in this paper,based on dynamic ray tracing effective neighborhood wave field approximation theory.By studying the nature and characteristics of normal distribution,the weight function based on normal distribution stack was derived and used in VSP stack imaging.All the sampling points in depth-time domain were converted into multiple sampling points of reflection points in offset-depth domain,in order to uniform the fold times of reflection points.Model test and the application in real data demonstrated that the VSP-CDP stack imaging method based on normal distribution weight function improved the VSP imaging precision.