基于立体层析反演的低频模型构建在深水区储层反演中的应用:以南海深水W构造为例

建立准确的低频模型是波阻抗反演中的重要环节，它直接影响着波阻抗反演结果的准确性。但是，常规模型建立方法的准确性受钻井数量影响明显，钻井数量越多，模型的准确性越高。在海洋深水油气勘探过程中，由于勘探费用昂贵，钻井数量非常少，很难通过常规方法建立准确的低频模型。特别是在沉积体横向特征变化较大时，地震反演的可靠性受到巨大影响。本文首先介绍了立体层析速度反演的基本理论和数据域、成像域立体层析速度反演的计算过程，综合数据域立体层析与成像域立体层析的优势获得了高精度速度模型；然后结合有限的钻井进行标定，构建出地震反演所需的低频模型，有效提升了低频模型的精度，使其达到可真实反映较大规模地质异常体的尺度；最后，将其应用于南海深水区W构造的勘探实践，提升了反演结果横向预测的准确性。

Construction of Low-Frequency Model with Three-Dimensional Tomographic Velocity Inversion and Application in Deep-Water Bock W of South China Sea

The establishment of an accurate low-frequency model is an important part of seismic impedance inversion, which directly affects the accuracy of the inversion results. However, the accuracy of the conventional model building method is significantly affected by the number of drilling wells, the more the number of wells, the higher the accuracy of the model. Due to the high cost of seismic exploration in deep-water, only a few drilling wells are available in this area; so it's difficult to establish an accurate low-frequency model as usual, especially when the deposition transverse features change largely, the accuracy of inversion result is impacted seriously. In this study, we introduced at first the basic theory of the three-dimensional tomographic velocity inversion and the calculation process of velocity inversion both in data and imaging domain, with taking the advantages of both data and imaging domain to get a high quality velocity model, then we constructed the low-frequency model for seismic inversion by combining with the velocity spectrum and well information, after this the accuracy and reliability of low-frequency model was improved effectively. We applied it to deep-water oil and gas exploration in bock W of South China Sea, and achieved the good results.