地球物理学进展 ›› 2018, Vol. 33 ›› Issue (5): 2020-2026.doi: 10.6038/pg2018BB0389

• 应用地球物理学Ⅰ(油气及金属矿产地球物理勘探) • 上一篇    下一篇

起伏地表叠前成像技术在川东高陡构造工区中的应用

谢万学(),李德珍,金德刚,何光明,彭文,陈丹   

  1. 中国石油集团东方地球物理勘探有限责任公司西南物探分公司,成都 610213
  • 收稿日期:2017-12-22 修回日期:2018-08-23 出版日期:2018-10-20 发布日期:2019-01-11
  • 作者简介:谢万学,男,1981年生,硕士,目前就职于中国石油集团东方地球物理勘探有限责任公司西南物探分公司,主要从事地震资料处理解释技术研究.

Application of pre-stack seismic imaging from rugged topography in complex structure survey of eastern Sichuan Basin

XIE Wan-xue(),LI De-zhen,JIN De-gang,HE Guang-ming,PENG Wen,CHEN Dan   

  1. BGP Southwest Geophysical Company, CNPC, Chengdu 610213, China
  • Received:2017-12-22 Revised:2018-08-23 Online:2018-10-20 Published:2019-01-11

摘要:

山前带地震资料成像问题是我国中西部油气勘探的难点之一.基于常规CMP浮动基准面的成像技术在陡缓转折带一般很难获得较准确的速度模型,在复杂地表及地腹条件下,无法对地下复杂构造进行精确成像.因此,本文提出一种基于地表一致性浮动面的双平方根动校正及起伏地表叠前时间偏移技术.该技术包括以下4个关键步骤:(1)地表一致性浮动面计算;(2)叠前地震道集预处理以提高道集信噪比;(3)双平方根动校正、速度分析及剩余静校正量迭代求取;(4)基于起伏地表的偏移速度分析及最终的叠前偏移成像.在数据叠前预处理阶段应用双平方根动校正技术,可有效提高剩余静校正及水平叠加速度拾取的精度.在偏移成像阶段应用起伏地表叠前时间偏移技术,可有效实现复杂髙陡构造的准确归位.在实际地震数据处理中,上述两个阶段的有机结合可以较好地改善复杂山前带地震工区的成像质量.该技术在四川盆地东部某潜伏构造三维工区中取得了较好的成像效果,证明了该方法的有效性.

关键词: 起伏地表, 成像, 地表一致性浮动面, 双平方根动校正, 叠前时间偏移

Abstract:

Seismic data imaging from rugged topography is one of the most difficult problems in mountainous areas of mid and western China.Conventional seismic processing technique with the assumption that all the shot-receiver traces are located on the same elevation will be confronted with great challenge for mountainous seismic surveys with rugged topography and complex substructure. The technique of processing from surface consistent floating datum is proposed to solve the problem. The procedure consists of four steps: (1) the calculation of surface consistent floating datum; (2) pre-processing of pre-stack seismic gathers which is aimed to improve the signal-to-noise ratio of seismic data; (3) implementation of double square root NMO (DSR-NMO), velocity analysis and iteration of residual statics computation; (4) migration velocity model updating and final pre-stack migration based on surface consistent floating datum. The application of double square root NMO in pre-processing stage can effectively improve the precision of stacking velocity analysis and residual statics calculation. The implementation of Kirchhoff pre-stack migration based on topography can get more accurate imaging results for complex structures in subsurface. The technology has been successfully applied to the mountainous field data in eastern Sichuan Basin with severe topography variation and complex subsurface geology structure. The imaging improvement of better event continuity and focusing can be observed obviously for both the DSR-NMO stacking and PSTM sections.

Key words: rugged topography, imaging, surface consistent floating datum, double square root NMO, pre-stack time migration

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