应用地震属性主成分分析识别古河道

利用曲率、相干等属性刻画河道的效果不明显，对这些属性的主成分分析效果较差。地震纹理、相干能量、谱峰值和分频振幅等属性虽然能较好地识别部分古河道，但是存在古河道刻画不全、识别范围有限等问题。为此，提出了应用地震属性主成分分析(PCA)识别古河道的方法，精细刻画了不同尺度古河道，预测效果优于单一属性，较好地提高了古河道识别精度。获得以下认识：(1)地震纹理、相干能量和谱峰值三种地震属性能够较好地刻画古河道，但是对古河道的识别结果不全面；利用PCA融合了三种地震属性识别河道的有效信息，可突出古河道的展布特征及边界形态。(2)基于分频瞬时振幅剖面对河道变化细节的识别差异，利用PCA融合不同频段瞬时振幅属性，以增强共性细节信息，提高了古河道识别精度。应用所提方法识别川西地区沙溪庙组河道，准确地反映了古河道的具体位置及轮廓。

Identification of paleochannels by seismic attribute principal component analysis

The effect of characterizing channels by using curvature and coherence is not obvious, and the performance of principal component analysis (PCA) on these attributes is poor. Although seismic texture, coherent energy, spectral peak, frequency division amplitude, and other attributes can identify some paleochannels well, there are some problems such as incomplete paleochannel characterization and limited identification range. Therefore, the method of seismic attribute PCA is proposed to identify paleochannels. The method finely characterizes paleochannels at different scales, and its prediction effect is better than that of a single attribute, which improves the identification accuracy of paleochannels. The following understandings are obtained: ①The three kinds of seismic attributes including seismic texture, coherent energy, and spectral peak can characterize paleochannels well, but their identification results of the paleochannels are not comprehensive. The effective information of channels identified by the three kinds of seismic attributes is fused by PCA, which can highlight the distribution characteristics and boundary morphology of paleochannels. ②According to the identification difference of channel change details by the instantaneous profile of frequency division amplitude, PCA is used to fuse the instantaneous amplitude attributes of different frequency bands to enhance the common detail information, which improves the identification accuracy of paleochannels. The proposed method is used to identify the channel in Shaximiao Formation in western Sichuan, and it accurately reflects the specific location and contour of the paleochannel.