叠前深度偏移网格层析速度反演技术在西湖背斜的应用

Application of Grid Tomography in Xi Hu Anticline

准噶尔盆地南缘西湖背斜近地表结构复杂,表层岩性变化大,目的层紫泥泉子组顶界埋深4 000 m,提高深度域速度精度困难。精确的速度建模是该区通过叠前深度偏移准确落实构造形态的关键。网格层析反演通过共成像点道集上的残余时差全局更新速度模型,提高速度模型精度,更适合山前带深度域模型迭代更新。研究及应用结果表明,该技术应用于类似山前带叠前深度偏移成像处理,可提高速度模型精度,得到的深度域成像精度高于以往叠前深度偏移处理结果。

The surface structure of Xi Hu anticline southern margin of the Junggar basin is complex, lithology change quickly in spatial,the top buried depth of target layer Ziniquanzi is 4000 m, improving the depth velocity accuracy is difficult,accutate velocity modeling is the key to make sure structural form through pre-stack depth migration in this area,the grid tomography inversion update velocity model by residual moveout of CRP gathers, which is more suitable for mountain front zone depth domain iterative model updating. The 3D pre-stack depth migration of Xi Hu anticline use the grid tomography velocity updating method to improve the accuracy of velocity model,well- seismic calibration confirmed,depth domain imaging accuracy is higher than that of the previous pre-stack depth migration processing results.The processing results show that this method can be applied to similar piedmont zone pre-stack depth migration processing in improving the accuracy of velocity model.