摘要
This paper reports a method for inversing interval velocity layer by layer according to VSP data,whose main feature is that the path of spread rays will be divided into linear transmission and refraction transmission,and then the interval velocity is inversed from top to bottom with VSP data.5 layers level medium model is designed on the basis of matlab,and then the ray tracing method is used to synthesize VSP records for three kinds of well-source distance(300 m,1 500 m,3 000 m).The result shows that the linear method is applicable to the small well-source distance,and refraction method is applicable to all kinds of well-source distance.