基于数据分段互双谱的海水深度计算方法

Seawater depth inversion based on segmented data cross-bispectrum

海水深度数据是开展OBC水、陆检资料合并处理的基础。结合时间序列高阶统计量提出了一种基于数据分段互双谱法的海水深度反演方法。通过对分段后的数据计算上、下行波场数据自双谱和互双谱,再计算相干互双谱和互相关谱,最后计算海水深度。水陆检数据分段计算,利用了叠加特性,增加了方法抗高斯噪声的能力。高阶统计量的互双谱和相干互双谱,具有压制高斯与非高斯有色噪声的优点。利用本文方法对OBC数据进行海水深度计算,结果与实测海水深度较吻合。计算的海水深度用于双检数据合并,压制海水鸣震干扰效果明显,为后续速度模型建立和偏移成像处理奠定了良好的基础。

The seawater depth is a basis for OBC dualsensor data summing.A seawater depth inversion method based on segmented data cross-bispectrum is proposed in combination with the time series higher-order statistics.First the auto-bispectrum and cross bispectrum of up-going and down-going wave field data are calculated from the segmented OBC data.Then the coherent cross-bispectrum and cross-correlation spectrum are calculated.Finally,the seawater depth is calculated and used for the OBC data summing.The OBC dual-sensor segmented data computation utilizes fully stacking characteristics,which increases the suppression of Gauss random noise.Cross-bispectrum and coherent cross-bispectrum of the higher-order statistics have the advantages of suppressing Gauss and nonGauss colored noise.Real OBC data seawater depths calculated by the proposed method match very well with measured seawater depths.These inversed seawater depths are used to dual-sensor data summing,and a good suppression of seawater reverberation is achieved,which lays a solid foundation for the subsequent velocity model building and migration.