Research Of Sedimentary Facies And Reservoir Characteristics Of The Second Members Of Xujiahe Formation In Anyue Area, Middle Of Sichuan Basin

Based on the principle and method of sedimentology and Reservoir Geology as well as Seismic Stratigraphy,by taking outcrop section,core,logging,seismic data as the research object, using various research methods, the reservoir characteristics of Xujiahe Formation in Anyue Area were studied and the sedimentary seismic and Facies of systematically analysed. Analysis of geological factors of high productivity wells,this provides a basis for the reservoir of predicting favorable zone.According to the study of Paleogeomorphic, The kind of trap is structural and lithologic trap. Fracture had been produced by differential compaction has increased Reservoir Property.Studies on several outcrop profiles and core data revealed that the 2th-6th members of Xujiahe Formation in the study area are all clastic deposits of shallow marine facies, dominated by estuary developed in an environment with a large tidal range. Beginning with introducing the basic principles of tidal deposition, this paper analyzes in detail the lithologic and structural features of the Xujiahe Formation. Its tidal origin is evidenced by bimodal cross bedding and cross lamination, interlayered bedding of thin sand and shale, dual clay ground structure, abrupt change of flow. Analyses of the sedimentary facies, microfacies and models of the Xujiahe formation show that most of the Xujiahe formation is of shallow marine estuary subfacies with a large tidal range consisting of various microfacies such as channel, mudflat, sand ridge sand bar, except for the margin where delta facies occur.The strata of the 2th member's sandstone of Xujiahe Formation were relatively stabilization. The sanstones of reservoir were maily mesograin to macrograin detritus quartz sandstone and fine to mesograin feldspar detritus quartz sandstone. The reservoir is a low and extra low porosity, low and extra low permeability reservoir, The proe structure belonged to the fine proe and minimal throat. It is recognized through evaluation that the reservoir types are fracture-pore.The Fracture,Structure(structural location and traps), Sedimentary Facies,etc. are the main geological factors of the high productivity wells. The tectonic cracks mainly developed in Local of small Structure and near fault. Indicating that favorable conditions of Fracture,the Fracture Reconstruction can be obtained commercial gas flow. Analysis suggests Fracture, Sedimentary Facies, Present structural location (traps), were the main influencing factors of Hydrocarbon prospective evaluation to exploration effects, and caused by Hydrocarbon prospective evaluation map of the second members of Xujiahe Formation in Anyue area,which were divided into four grades.