复杂近地表层析反演与波场延拓联合基准面校正

在复杂近地表条件下采集的地震资料，由于地形起伏剧烈，低、降速带变化大，采用传统的垂向时移静校正方法会使地震波场发生扭曲，降低速度分析精度，影响资料的最终成像质量。近地表层析反演与波场延拓联合基准面校正的方法有利于解决复杂近地表条件下地震资料的静校正问题。其应用思路是先采用折射波层析反演得到近地表模型，再根据修正后的近地表速度模型分别对检波点和炮点进行波场延拓。具体实现步骤是：将水平基准面置于地形之上，根据惠更斯-菲涅尔原理和波场互易原理以及炮、检点的空间分布位置，以地表接收到的地震数据为二次震源，将检波点和炮点分别先向下、后向上延拓到水平基准面上，从而实现复杂近地表地区地震数据处理的层析反演与波场延拓联合基准面校正。

Combined datum correction of tomography inversion with wavefield continuation under complex near surface condition

Under complex near surface condition,the terrain fluctuates acutely.Therefore,the low-velocity and subweathered zone chan- ges considerably.The traditional plumb time-shift static correction may distort seismic wavefield and decrease the accuracy of velocity analysis,ultimately impact the imaging quality.The combined da- tum correction of tomography inversion with wavefield continuation is beneficial for solving static correction problem under complex near surface condition.Firstly,the near surface model is obtained by refraction tomography inversion.Then,the wavefield continua- tion is carried out on shot point and receiving points in terms of the modified near surface velocity model.The detailed steps are that 1) the level datum is set above terrain;2) based on Huygens-Fresnel theory and wavefield reciprocity principle,as well as the spatial distribution of shot and receiving points,taking the received seis- mic data on surface as the second focus,the continuation is carried out on shot and receiving points upwards and downwards to level datum respectively.Consequently,the conbined datum correction of tomography inversion with wavefield continuation is realized.