Study On The Sedimentary Characteristics And Sedimentary Facies Of The Eogene Shahejie Formation In The Western Beach Area Of Liaohe Basin

Eogene Shahejie Formation in the western beach area of Liaohe Basin has a great petroleum geologic potential. It is an important substitute area for the further exploration and development in Liaohe Oil Field. Because of the limit of exploration data, the previous research of this area is relatively inadequate and lacks systematic comprehensive understanding. Therefore, it is important to study the sedimentary characteristics and the distribution pattern of sedimentary facies in this area.In the paper, based on a large number of cores in the macroscopic and microsopic characteristic description, according to logging, seismic, analysis assay data and other data, a further and detailed analysis is carried on for the sedimentary characteristics, sedimentary facies, sand body distribution, sedimentary model and sedimentary evolution of the Eogene Shahejie Formation in the western beach area of Liaohe Basin.First, this paper detailedly summarizes various facies marks from rock composition, sedimentary structure, particle size distribution, paleontology, logging facies, seismic facies and other aspects, and estabish a solid basis for identification and classification of the sedimentary facies of the western beach area of Liaohe Basin. Second, the study determines that there are five sedimentary facies types including fan delta, braided delta, nearshore subaqueous fan, sublacustrine fan and beach bar, according to the identification of facies marks as well as comprehensive analyses of the content of conglomerate and sandstone, sandstone thickness, mudstone color, detrital composition and other data of Shahejie Formation in the western beach area of Liaohe Basin. There are three main provenance areas consisted of western uplifting, Huludao uplifting and central low uplifting. Western uplifting provides clastic matters for west slope belt which mainly develops braided delta and sublacustrine fan. Huludao uplifting provides clastic matter for its periphery area which mainly develops fan delta. Central low uplifting provides clastic matter for eastern steep slope belt which mainly develops fan delta and nearshore subaqueous fan. During the study, there are few drilling wells and they unevenly distribute in the area of the western beach area of Liaohe Basin. This paper proposes and adopts a series of new technologies and methods for analysis, including technique of FCM multi-attribute clustering seismic facies automatic division, multi-attribute neural network sand body prediction technique, palegeomorphic restoring technique, and wavelet transform time-frequency analysis technique. It improves the reliability of sedimentary facies analysis.According to the study of the sedimentary characteristics and sedimentary facies in sequence stratigraphic framework of the Eogene Shahejie formation in the western beach area of Liaohe Basin, this paper defines the sedimentary facies distribution and temporal and spacial evolution pattern within each sequence, and discusses controlling function of factors such as structure, paleogeomorphy and provenance. In the period of low stand systems tract (LST), sand body is easy to catch petroleum. Sedimentary microfacies distribution of LST is analyzed in the key areas of slope belt of Lingnan. At the same time, by using wavelet transform time-frequency analysis technique, this paper proposes sedimentary microfacies such as underwater braided channel, mouth bar and beach bar which have different time-frequency characteristics. It boosts the exploration of this area greatly.