The Analysis Of Sedimentary Facies Of South Dagang Oilfield Of The Upper Paleozoic In Huanghua Depression

The study area is located in the central and southern of Huanghua depression, the north is bounded by Yanshan fold belt, the east is bounded by Chengning Uplift, the west is bounded by Cangxian Uplift。Their changes of structural characteristics and lithology are complex, the research of Predecessors is only partial describtion of sedimentary facies。there is no overall detailed analysis of sedimentary facies, this article uses sedimentology and sequence stratigraphy theory, based on the analysis of core, logging data interpretation, logging and assay data, establishing for the stratigraphic classification scheme of the special geological conditions, the evolution and the distribution of sedimentary facies in the study area is a detailed analysis, In order to further meet the market demand of oil and gas, we need to find a new area fulled of oil and gas, it is important to expanding areas of exploration.Based on the research in the study area, we mainly concluded the following understanding:The word location mainly develops barrier island coast sedimentary system、 delta sedimentary system and Meandering river river sedimentary system, The distribution of the specific are following:Benxi Group and Taiyuan Group of carboniferous mainly develops barrier island coast sedimentary system, the phase type of Benxi Group is platform facies, and lagoon facies.. the phase type of Taiyuan Group is tidal flat facies, lagoon facies, and swamp facies. The Shanxi Group of Permian mainly develops delta sedimentary system, It consists of delta plain and delta front subfacies, The delta plain is more development, the development of delta front subfacies is not well. the development of microfacies types are mainly distributary channel microfacies and swamp microfacies. The Xiashihezi Group、Shangshihezi Group and Shiqianfeng Group of Permian mainly develop Meandering river fluvial facies sedimentary system. The types are river bed, levees and flood plains, Microfacies types are mainly sedimentary microfacies in the riverbed detainment, point bar microfacies and river flood lakes, flood land and river flood swamp microfacies etc.Lithology of each group in the study area is different, The lithology of platform facies in carboniferous is given priority to grey limestone and bioclastic limestone. The lithology of Lagoon facies is given priority to mudstone, silty mudstone and clay rock.the lithology of Tidal flat facies is given priority to gray fine-grained sandstone,mudstone. The lithology of Swamp facies is given priority to mudstone,black mudstone and coal. The lithology of Shanxi Group is given priority to gray sandstone and mudstone with several sets of thin coal seam in the middle.The lithology of Xiashihezi Group、Shangshihezi Group and Shiqianfeng Group is complex,it mainly contains the glutenite of riverbed detainment sedimentation and sandstone of beach sediment. In the flood plain deposits, The lithology is brown sandstone and mudstone. The phenomenon of sand and mud appear alternately.According to field profiles in the study area and outcrop, core, logging data and logging data, we established the single well sedimentary facies map,it enables us to well know the rule of variation of sedimentary facies in vertically. understanding the sand body in the distribution characteristics of each layer in the group and the main layer of coal seam group, it also can provide the basis for the next exploration targets. On the basis of single well sedimentary facies map, we have been estabed three well profile of sedimentary facies, according to the work area of well data. Knowing the overall distribution of the coal seam and the spatial distribution law of sand body, we can determine the selected main target zone and advantages of the distribution of reservoir and provide technical support for further exploration and deployment. At the same time the well sedimentary facies affected by source、the ancient terrain and transgressive. Benxi Group and Taiyuan Group in carboniferous mainly influenced by the ancient terrain and transgressive. the water embodied in from the southeast of the sea, along the north west transgression, influenced by the ancient terrain, higher ground, it mainly develops the lagoon facies and tidal flat facies. But Shanxi Group Xiashihezi Group and Shangshihezi Group are mainly influenced by ancient terrain and source, because the water regressived along the channel southeast during this period, the north mixed with all kinds of suspended matter deposits here.so the Shanghezi Group and Xiashihezi Group develops Fluvial facies. in Shanxi Group it mainly develops Delta plain deposits of Delta Facies.We draw out of the sand body contour map according to each interval sand body distribution, we Draw out of the floor plan of sedimentary facies in understanding the source direction and sand body, on the basis of contour, we know the distribution of sedimentary facies in the plane,we established. sedimentary facies model of each according to source direction of sedimentary facies and its change trend.