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地层对地震波的衰减性质通常用品质因子来度量。针对零偏VSP资料的特点,利用其不同传播距离的直达波信息,采用频谱比值方法进行品质因子的提取,并分析了信噪比对品质因子提取结果的影响。地震资料噪音水平越高,可以利用的频谱比值计算范围越小,计算误差越大。对理想子波和实际模型零偏VSP资料的处理结果表明了该方法的有效性和可靠性。利用垦71-检41井零偏VSP资料求取了品质因子随深度的变化,结果与对应的地层性质吻合较好,并且随着深度的增加,品质因子提取的可靠性逐渐增强。这为利用品质因子研究储层性质以及进行反Q滤波提高地震资料分辨率提供了基础参数。
The decay properties of the seismic wave to the formation are usually measured by the quality factor. According to the characteristics of zero-offset VSP data, the direct-wave information of different propagation distances is used to extract the quality factor by spectral ratio method and the influence of signal-noise ratio on the quality factor extraction result is analyzed. The higher the noise level of seismic data, the smaller the calculation range of the available spectrum ratio, the larger the calculation error. The processing results of the ideal sub-wave and the actual partial-offset VSP data show that the method is effective and reliable. Based on the VSP data of Ken 71-41 well, the variation of quality factor with depth is obtained. The result is in good agreement with the corresponding stratigraphic properties. With the increase of depth, the reliability of quality factor extraction is gradually enhanced. This provides the basic parameters for using the quality factor to study reservoir properties and performing inverse Q filtering to improve the resolution of seismic data.