高精度深度域层析速度反演方法

深度域层速度场是叠前深度偏移最重要的参数，直接决定了偏移成像的精度。传统层析速度建模方法由三部分组成，首先利用Dix公式或基于层位约束的Dix公式生成初始层速度模型，然后利用炮检距域道集对初始速度模型进行层析迭代，最后利用网格层析方法局部修饰速度模型。本文改进了传统层析速度建模流程：首先利用炮域波动方程相干反演方法建立初始速度模型，再利用角度域共成像点道集进行层析迭代，最后利用基于层位约束的网格层析方法局部修饰速度模型。渤海M区块三维实际数据试算证明本文对层析速度建模流程的改进是有效的，改进后的新流程可以大幅提高层速度场的精度。

High-precision velocity tomography inversion in the depth domain

The velocity field in the depth domain is the most important parameter of prestack depth migration,which directly determines the migration imaging accuracy.Conventional tomography velocity modeling methods consist of three parts.First,an initial interval velocity model is generated with Dix formula or horizon-constraint Dix formula.Then the initial velocity model is iterated by offset-domain gathers.Finally,the velocity model is modified by the grid tomography.In this paper,we improve the flow of conventional tomography velocity modeling.First an initial velocity model is established with the wave-equation coherent inversion.Then the tomography iteration is carried out by common-imaging-point gathers in the angle domain.Finally,the velocity model is locally modified by the grid tomography method based on horizon constraints.Experimental results of 3D data in the Block M,Bohai Sea show that the improved flow can greatly improve the interval-velocity field accuracy.