Sedimentary Facies Of The East Section Of The Chahe Formation Structure

Chaheji Structural Belt is located in the west of Baxian Depression and Niutuozhen Convex, which mainly developed into NE and NW oriented fractures. The formations found in the boring are Paleogene Kongdian Fm, Shahejie Fm, Dongying Fm, Neogene Guantao Fm, Minghuazhen Fm and Quaternary Pingyuan Fm from the bottom to top. In this paper, the multi-disciplinary theory was used as a guidance, macro and micro aspects were combined, core observation and description were studied, the assay data of core and paleontology were analyzed, and the seismic facies and electrofacies response characteristics were learned for the study sedimentary facies of D3Memberformation, and the following conclusions were drawn:l)According to the data of Chaheji, four third-order sequences were divided, respectively equivalent to Members Es1, Ed3,Ed2and Ed1.2)According to the lithology, sedimentary structure, grain structure, paleontology and electrofacies, the sedimentary microfacies of single well were divided to shallow water delta and lacustrine facies, and the former were dominant. The shallow water delta facies were divided into plain and front subfacies, the delta plain subfacies could be subdivided into distributary channel, interdistributary bay and natural levee microfacies, and the delta front subfacies could be subdivided into underwater distributary channel, interdistributary bay, underwater natural levee, distributary mouth bar, sandbar and mudflat microfacies.3)According to the composition and distribution of heavy minerals, rock composition, sandstone distribution and seismic data, the major sediments came from the west, there were provenances in the north block from north and there were secondary provenances in the south block from southwest.4)It was concluded in the study of the reservoir physical properties of different sedimentary microfacies in the area that the (underwater) distributary channel microfacies had the best reservoir properties, mostly medium porosity and medium permeability reservoirs; the sand bars had relatively good reservoir properties, mostly medium porosity and low permeability reservoirs; the sand bodies of natural levees and underwater natural levees had poor reservoir properties, mostly low porosity and permeability reservoirs; interdistributary bay microfacies were mostly ultra-low porosity and low permeability sand bodies. On the basis of the reservoir physical properties of different sedimentary microfacies and in combination with the well test data, the productivity of sedimentary facies was analyzed and the conclusion was drawn as follows:the sand bodies of delta distributary channel were high productivity areas, the distal bar, mouth bar and meander bank facies reservoirs were high productivity areas, and the natural levees were low productivity areas.