摘要
传统二阶动校正方法基于较小最大偏移距与目标层深度比和地震波沿直线传播假设,进行长偏移距地震资料处理时,这些假设不再成立.高阶项动校正公式能提高长偏移动校正精度,文中对几种典型的高阶项动校正方法进行了比较,并提出了优化四阶、优化六阶动校正方法.模型计算表明,高阶项动校正方法能取得较常规动校正方法好的动校正结果,但并非阶数越高动校正精度就越高;在纵向速度变化剧烈时,高阶动校正或优化高阶动校正方法一般不能适用于最大偏移距与目标层深度大于3.5的地震反射同相轴,优化四阶和优化六阶动校正公式由于考虑了无穷大偏移距的影响,具有更稳定、更加精确动校正效果,适合于实际的各向同性长偏移距地震资料处理.
The second-order Normal moveout equation is based upon two hypotheses. They are the small offset and simple straight ray model. These hypotheses are invalid when seismic events with long-spread are processed. Normal moveout formulae with higher-order terms can improve NMO precision. In this paper, we compare several higher or der NMO formulae and propose optimal fourth-order NMO formula and optimal sixth-order NMO formula. The numerical computation results show that higher-order formulae can get better NMO output and the NMO precision is not improved with higher values of the maximal order at all time. if vertical velocity gradient is strong. None of the formulae can achieve satisfying NMO result when the ratio of maximal offset to objective depth is more than 3.5. Optimal fourth-order and optimal sixth order formulae are more steady and more precise and more appropriate for field seismic data processing because the influence of infinite offset is corrected in those formulae.
出处
《地球物理学进展》
CSCD
北大核心
2008年第4期1173-1178,共6页
Progress in Geophysics
关键词
各向同性
长偏移距离
高阶动校正
地震同相轴
homogeneous and isotropic, long-spread seismic data, higher-order terms, normal-moveout correction,seismic events
