The Study on Method of Depositional Microfacies Discrimination with Well-logging Information

Key words: 
• neuraI network /
• depositionaI microfacies /
• facies signs /
• compIex IithoIogy

Abstract: different depositionaI microfacies can be identified by the combination of facies signs. The reIation between facies signs and depositionaI microfacies can be estabIished by the paraIIeI reaction of NeuraI Network basic processing units. Sedimentary microfacies signs can be obtained directIy by the observation and anaIysis of rock core and it can be aIso got indirectIy by weII Iogging information. In this paper, we use modern artificiaI neuraI network（ANN）pattern recognition technigue to interpret the Iithofacies with conventionaI weII-Iogging data and depositionaI structure with dip weII-Iogging data. In determination of Iithofacies, eight to ten weII-Iogging curve（SP, GR,... ）are used. The coincidence rate of Iithofacies is eighty to ninety percent in the standard weII and seventy to eighty percent in non standard weII. ANN was aIso used to anaIyze Iogging facies and depositionaI environment for singIe-weII or muIti-weII on the same sedimentary background. The method of using Iogging data to automaticaIIy identify the carbonate sedimentary microfacies was found out. In the sedimentary microfacies modeI, 24 facies signs that are the combination of Iithofacies（category and structure ）, sedimentary structure（scoured base, bedding type and the change of Iaminae ）, the direction of paIeocurrent, the IithoIogicaI change, the feature of curve ampIitude, the form of curve, the cycIe of sedimentation, the pattern of angIe and direction of dip, pore structure etc. are used. The modeIs offshore deposit and bioherm facies are buiIt up. The method has been used in the fieId of Si Chuan, Xin Jiang, Liao He and Hua Bei and so on. After testing with some exampIes, the method is proved to be effective to resoIve the probIem of petroIeum expIoration in oiI fieId.