In the conventional offshore seismic data,the information lower than 6～8 Hz is normally absent,and the number of wells drilled in deep water is very limited and extremely uneven.Therefore,it is difficult to establish accurate low frequency models through conventional methods,which would influence the accuracy and reliability of seismic impedance inversion greatly.Addressing to these problems,an economic and efficient method to achieve offshore broad-band seismic inversion was proposed.Firstly,the seismic frequency division technique based on 5-parameter generalized S-transform is used to compensate the missing low-frequency and broaden the frequency band.Secondly,a more accurate low-frequency model is established through the 3D tomographic velocity inversion,which can clearly present the structural changes of the underground geological body,and solve the problem of constructing the low-frequency model without or with few reference wells.Lastly,the procedure of obtaining wavelet for broad-band seismic inversion was proposed,where the side lobes were pressured and the spectrum has been widened obviously.This method was applied for the reservoir predication of W structure in the Pearl River Mouth basin,and effectively improved the accuracy of seismic inversion and provided the technical support for exploration and development in the deep water,enjoying a good application potential.%海上常规地震资料中普遍缺失6～8Hz以下低频信息,加之钻井数量非常少且分布极不均匀,很难通过常规方法建立准确的低频模型,从而影响着地震波阻抗反演的精度和可靠程度.提出了一种经济、高效实现海上宽频地震反演的方法,首先利用基于5参数广义S变换的分频技术高效补偿地震中缺失的低频信息,拓宽了资料频带;其次通过立体层析速度反演构建更为精确的低频模型,更好地反映了地下地质体的结构性差异变化,解决了少井、无井情况下低频模型构建的难题;最后提出了针对宽频地震资料反演的子波求取步骤,提取的子波旁瓣得到了明显压制,频谱宽度有了明显拓宽.在南海珠江口盆地深水区W构造储层预测中的应用表明,本文方法有效提升了地震反演精度,为深水区油气勘探开发提供了技术支持,具有很好的应用推广价值.
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