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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。
Dynamic correction is very important for long-offset seismic data, especially deep-reflected seismic data. Traditional hyperbola correction methods based on the short offset assumption or dynamic correction methods based on the even fractional expansion will fail at long offsets. Based on Padé approximation, this paper proposes a new method of long offset dynamic correction suitable for isotropic media. The theoretical analysis and numerical experiments show that the proposed method is more effective than other known methods for dynamic correction at long offsets. The traditional motion correction method has an error of more than 5 ms when the ratio of offset to depth is 2, and the error is more than 10 ms when the ratio is 3. In contrast, the [3,3] -order Padé approximation kinematic correction method does not exceed 5ms at offset-to-depth ratio of 3. In the flat-layer model experiment of Tirrawarra well data synthesis in the Cooper Basin, the effective range of the offset and depth ratios of [3,3] -order Padé approximation methods is more than twice that of other dynamic correction methods. The accuracy of the [7,7] -order Padé approximation method is further improved than the [3,3] -order Padé approximation.