Normal moveout for long offset in isotropic media using the Padé approximation  

基于Padé逼近的各向同性介质长偏移距动校正（英文）

作　　者：Song Han-Jie Zhang Jin-Hai Yao Zhen-Xing 宋汉杰;张金海;姚振兴(中国科学院地质与地球物理研究所,地球与行星物理重点实验室,北京100029;中国科学院大学,北京100049)

机构地区：[1]Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China [2]University of Chinese Academy of Sciences, Beijing 100049, China

出　　处：《Applied Geophysics》2016年第4期658-666,738,739,共11页应用地球物理（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.41130418 and 41374061);the National Major Project of China(No.2011ZX05008-006)and the Youth Innovation Promotion Association CAS(No.2012054)

摘　　要：The nomaal moveout correction is important to long-offset observations, especially deep layers. For isotropic media, the conventional two-term approximation of the normal moveout function assumes a small offset-to-depth ratio and thus fails at large offset-to-depth ratios. We approximate the long-offset moveout using the Pade approximation. This method is superior to typical methods and flattens the seismic gathers over a wide range of offsets in multilayered media. For a four-layer model, traditional methods show traveltime errors of about 5 ms for offset-to-depth ratio of 2 and greater than 10 ms for offset-to-depth ratio of 3; in contrast, the maximum traveltime error for the [3, 3]-order Pade approximation is no more than 5 ms at offset-to-depth ratio of 3. For the Cooper Basin model, the maximum oft＇set-to-depth ratio for the [3, 3]-order Pade approximation is typically double of those in typical methods. The [7, 7]-order Pade approximation performs better than the [3.3]-order Pade armroximation.动校正对于长偏移距地震资料尤其是深层反射的地震资料十分重要。基于短偏移距假设的传统双曲动校正方法或者基于连分式展开的动校正方法在长偏移距会失效。本文基于Padé逼近提出了一种适合于各向同性介质的长偏移距动校正新方法。理论分析和数值实验结果表明:该方法在长偏移距的动校正效果明显优于其它已知的动校正方法。传统动校正方法在偏移距与深度比值为2时误差超过5ms,该比值为3时误差超过10ms。相比之下,[3,3]阶Padé逼近动校正方法在偏移距与深度比值为3时的误差不超过5ms。在Cooper盆地Tirrawarra井数据合成的平层模型实验中,[3,3]阶Padé逼近动校正方法的偏移距与深度比值有效范围是其他动校正方法的两倍以上。[7,7]阶Padé逼近动校正方法的精度较[3,3]阶Padé逼近具有更进一步的提升。

关 键 词：Pade approximation long offset normal moveout isotropic medium 

分 类 号：P631.44[天文地球—地质矿产勘探]