【摘要】 川西坳陷丰谷构造须家河组四段属典型的陆相含煤地层,广泛发育辫状河三角洲沉积。首先根据岩心描述、岩石薄片观察及砂体测井曲线形态分析等,在须四段识别出水下分流河道、分流河道间、河口坝、远砂坝、水下天然堤和前三角洲泥等6种沉积微相;其次针对丰谷构造井资料较少、砂泥岩速度差异不大的特点,采用神经网络的地震多属性反演得到自然伽马数据体;最后,以次为约束,建立泥质质量分数三维模型,预测泥质质量分数的空间变化,分析沉积微相演化规律。研究表明:须四段垂向经历了完整的水进—水退过程;沉积早期和晚期砂体较厚,主要为多期水下分流河道的拼接和叠置;沉积中期砂体相对较薄,发育河口坝与残余水下分流河道,砂体间有厚度稳定的前三角洲泥。更多还原

【Abstract】 The fourth section of Xujiahe Formation in Fenggu Structure of western Sichuan Depression is typical continental coal-bearing strata and widely develops the braided river delta.According to core description,rock slice observation,analysis of logging curve shape,underwater distributary channel,inter distributary,mouth bar,distal bar,underwater natural levee and prodelta mud are identified in the fourth section of Xujiahe Formation.In view of little well data and small velocity difference between sandstone and mud in Fenggu Stucture,the data volume of natural gamma is inverted by using multiple seismic-attributes inversion based on neural network.Three-dimensional model of shale content is established in order to predict the spatial variation of shale content and to analyze the evolution law of sedimentary microfacies.The results show that the fourth section of Xujiahe Formation experiences the complete process of transgression to regression.At the early stage and late stage of deposition,sand bodies are very thick and are mainly the splice and superimposition of multiphase underwater distributary channel.At the middle stage of deposition,sand bodies are relatively thin and mouth bar and residual underwater distributary channel develop and stably thick prodelta mud distributes among sand bodies.更多还原