复杂构造地震叠前深度偏移速度模型构建及效果

The Pre-Stack Depth Migration Velocity Model for Complex Geological Structure in Southern Margin of Junggar Basin: Modeling and Effect

准噶尔盆地南缘独山子地区近地表结构复杂,地下构造多表现为上陡下缓的形态,断裂发育,波场极其复杂,给地震叠前深度偏移成像造成困难。论述了独山子地区地震叠前偏移速度模型构建的几个关键环节:首先充分利用该区的钻井资料建立区域层速度量版,消除近地表西域砾岩对下伏地层速度的影响;其次通过测井速度资料对地震速度进行约束校正,采用沿层相干反演等层速度反演方法提高速度模型的精度,最终对二维网格开展拟三维速度模型的建立,确保了二维网格速度场空间和时间上的闭合,叠前深度偏移取得了良好的成像效果。

Dushanzi area in the southern margin of Junggar basin is characterized by complex near-surface, strut：lure, up-steep and down- gentle geological structure style, fauh development and very eomplicated wave fiehls, which give rise to difficulties in the pre-stack depth migration in this area. This paper presents the key procedures for the seismic pre-stack depth migration velocity model （PSDM） applied in I）usbanzi area： （1） making filll use of well data to establish interval velocity map, and eliminate the influence of near-surihce Xiyu conglom- erale on the underlying interval velocity： （2） making restricted correction of the seismic velocity using drilled well velocity data and improv- ing the accuracy of tire velocity model with along-layer coherent inversion; （3） establishing the 3D velocity model based on tire 2D grid to ensure tire closure of space and time in 2D grill velocity field. The ease study shows good imaging effects by using the PSDM technology.