SP测井小波变换在单井层序划分中的应用

Application of SP Logging Wavelet in Sequence Division of Single Well

利用单井自然电位(SP)测井曲线经coif5小波变换,结合露头剖面传统层序地层划分标准,探讨了小波变换曲线与鄂尔多斯盆地南部A井三叠系陆相延长组三级层序界面的对应关系。结果显示,SP测井曲线经coif5小波变换后的d12小波(SP_coif5_d12)极大值可能对应湖退—湖侵旋回转换面(即层序界面);而小波曲线的极小值对应最大湖泛面,SP_coif5_d12小波可以作为湖盆的三级层序划分指标,说明coif5小波变换极值点位置检测到的SP测井信号与层序界面具有对应关系。该方法非常简捷,在陆相湖盆层序地层研究中具有实际应用价值,尤其适于缺乏岩心和地震等资料的单井研究。

After the SP log of single well having experienced coif5 wavelet conversion,combined with traditional sequence stratigraphy classification criterion of outcrop profile,this paper discussed the corresponding relationship between the wavelet conversion curve and the continental Triassic Yanchang Formation third order sequence boundary in well A of Southern Ordos Basin. The study results showed that after the SP log having experienced coif5 wavelet conversion,the maximum value of d12 wavelet( SP_coif5_d12) might correspond to the lake regression- lake transgression cycle conversion surface( i. e.,sequence boundary); whereas the minimum value of d12 wavelet corresponded to the maximum flooding surface; therefore,the SP_coif5_d12 wavelet could be taken as the third order sequence classification indices of lake basin,indicating that the SP logging signal detected at the coif5 wavelet conversion extreme point had a corresponding relationship with the sequence boundary. This method is very shortcut,has practical application value in the sequence stratigraphy research of continental lake basin,and is especially applicable to the study of single well short of core and seismic data.