Abstract: Quantitative description of sedimentary microfacies is an effective way to study reservoir. This paper selects natural gamma and spontaneous potential logging curve to use their  root-mean-square, skewness and the average amplitude between the upper and lower within bed limit to serve as indexes in quantitative identification of sedimentary microfacies. The average amplitude of logging curve is used to classify as small and medium curve. Data skewness within bed limit is used to be a quantitative parameter to determine the curve stability and shape, which is employed to identify the stable and unstable curves. The average range of the upper and lower amplitude within bed limit is used to further ensure the morphology of logging curve. By using this method,  many microfacies such as meandering stream channel, beach, crevasse splays, natural levees and flood plain, have been identified in meandering stream deposits of Shahejie formation, Qudi oilfield, which validates this method. 

Key words: quantitative description, meandering stream, logging curve amplitude, mean amplitude value 

摘要： 定量描述沉积微相是进行储层精细表征的有效手段。选取自然伽马和自然电位测井曲线幅度值的均方根、偏度及分层范围内上下两部分平均幅度值作为定量判断沉积微相的参数值。利用测井曲线幅度均值的大小判断曲线的起伏高低，划分出小幅度曲线和中幅度曲线；将分层范围内数据点的偏度作为判断曲线稳定性和形态特征的定量参数，识别出稳定型的曲线和不稳定型的曲线；最后利用层内上下两部分平均幅度均值差，进一步确认测井曲线的形态。利用该方法，以曲堤油田沙河街组曲流河沉积为对象，识别出了曲流河河道、边滩、决口扇、天然堤及泛滥平原等沉积微相，证明该方法具有很好的可行性。 

关键词: 定量描述；曲流河；测井曲线幅度；幅度均值