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Quantitative Analysis of the Log Facies of Wutonggou Formation in Tainan Depression of Tuha Basin
Zhang Yingnan, Yang Shaochun
The sedimentary process of Wutonggou formation is controlled by coastal underwater alluvial fan and alluvial fan in the Tainan depression of Tuha basin. For the complicated sedimentary setting, it's difficult to identificate the microfacises with lacking of systematic studies on log facies. The representative sedimentation microfacies with obvious facies marker were selected to make contrast and summarize up the features of well loggs. The model was established for different microfacies. The first 11 lowfrequence wavelet coefficients can perform well in reconstructing variation trend of GR log. There are significant differences in the wavelet coefficients and reconstructed lowfrequence curves and highfrequence curves among different sedimentation microfacies. The variation law of lowfrequence wavelet coefficients in every microfacies was analysized from the hydrodynamic force and other sedimentology aspects. By doing these, the abstract information of sedimentation microfacies belonging to geological space was converted into specific low dimensional feature vector of digital space. Based on this point and combing the characteristic of lowfrequence curves and highfrequence curves, a set of sedimentation microfacies identification templates was established. Sedimentation microfacies were identified by calculating the minimum Euclidean distance of logging curves between small layer and identification templates, with the combination of comparing the characteristic of lowfrequence curves and highfrequence curves between them.
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