Reservoir diagenetic facies and its logging identification of Es4s in Langgu sag

Based on bulk analyses of core observation, thin section identification, image analysis and fluid-inclusion analysis, the diagenesis types of reservoirs in the upper part of the fourth member of the Shahejie Formation (Es4s) in Langgu Sag were studied. Moreover, the diagenetic evolution sequence was established. On this basis, the classification and naming methods of diagenetic facies again and four typical diagenetic facies assemblages in the reservoirs of Es4s in Langgu Sag were discussed. Using the well-log curve characteristics of natural gamma, resistivity and acoustic time, Fisher typical discriminant was adopted to determine the quantitative discrimination functions of each diagenetic facies assemblages, and the logging parameters cross plot of each diagenetic facies assemblages were established. On the basis of meticulous analysis on reservoir diagenetic facies assemblages of the typical well sections using the casted thin section analysis and logging identification, combined study of sedimentary facies, and the distribution of the reservoir sedimentary-diagenetic facies assemblages of Es4s in Langgu Sag was analyzed. The results show that type I diagenetic facies assemblages mainly distribute in the root and some inner-middle part of nearshore subaqueous fan in Jiuzhou-Guan structural belt. Type II diagenetic facies assemblages mainly distribute in the braided river delta of the northern Hexiwu structural belt and the edge of nearshore subaqueous fan in Jiuzhou-Guan structural belt. Type III diagenetic facies assemblages mainly distribute in the braided river delta of the middle-southern Hexiwu structural belt. Type IV diagenetic facies assemblages mainly distribute in the braided river delta of southern Hexiwu structural belt and Liuquan-Caojiawu structural belt. © 2015, Central South University of Technology. All right reserved.