山前带复杂构造成像中叠前深度偏移方法研究及应用

Research and Application of Pre-stack Depth Migration Method in Piedmont Complex Structure Imaging

西部前陆盆地高陡复杂构造带地震资料的准确成像已经成为制约该类地区地震勘探的瓶颈,传统的地震成像方法由于其自身算法及适应性的限制在这类地区难以准确成像,因此很有必要开展叠前深度偏移方法研究。首先从理论上分析了Kirchhoff积分法叠前深度偏移的原理及优势,介绍了主要技术措施和实现方法;然后针对常规地震资料信噪比低,高陡构造偏移归位困难等问题,实现了一种叠前时间偏移、叠后和叠前深度偏移相结合,运用最佳拟合法准确求取速度模型;最终实现叠前深度偏移,准确落实构造的方法。此外,针对二维测线资料偏移效果,对比分析验证了叠前深度偏移方法在山前带复杂构造成像中的有效性。

Piedmont high and complex structure imaging of the western foreland basin has become bottleneck of seismic exploration. The conventional seismic imaging method couldn＇t get correct imaging because of the limit of its algorithm and adaptability. We analyses the advantages of pre-stack depth migration of Kirchhoff integral method, and introduce its main techniques. Aiming at such problems as low signal to noise ratio of the normal seismic data, and difficult to migrate high and steep structure and so on, we achieve a method that combines with pre-stack time migration, post-stack depth migration and pre-stack depth migration, and uses the best fitting method to obtain velocity model exactly, to do pre-stack depth migration, and to achieve actual structure finally. Finally the comparison analysis aiming at 2D survey lines of piedmont zone confirms the effectiveness of the pre-stack depth migration method for piedmont complex structure imaging.