关键词: 台南凹陷, 测井相, 定量分析, 沉积微相, 小波系数

Abstract: 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 lowfrequence wavelet coefficients can perform well in reconstructing variation trend of GR log. There are significant differences in the wavelet coefficients and reconstructed lowfrequence curves and highfrequence curves among different sedimentation microfacies. The variation law of lowfrequence 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 lowfrequence curves and highfrequence 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 lowfrequence curves and highfrequence curves between them.

Key words: Tainan depression, Log facies, Quantitative analysis, Sedimentary microfacies, Wavelet coefficients