Sequence Stratigraphy And Sedimentary Facies Of Ordovician Carbonate Rocks In The North Slope Of Central Tarim Basin

The northern slope of central Tarim basin is located in the central part of the central uplift of the Tarim Basin,with the central Tarim basin No.1 fault zone in the west and the Mangare sag in the east.Comprehensive two-dimensional and three-dimensional seismic data,drilling wells,cores and other materials,guided by the classical sequence stratigraphy,sedimentology,seismic stratigraphy and other disciplines,the sequence of the Ordovician carbonate rocks on the northern slope of the Tazhong area Stratigraphic and sedimentary facies studies have established a sequence stratigraphic framework and sequence deposition filling model in the whole work area.The main controlling factors of the third-order sequence sedimentary characteristics and sequence evolution are analyzed.The seismic facies and sedimentary facies types and planes are studied.The law of cloth is used to investigate the sedimentary characteristics of the reef-shoal facies in the three-dimensional area,and provide geological basis for finding the reef-shoal reservoirs in the north slope of the central Tarim basin area.Using seismic response characteristics and single well sequence division to identify and calibrate the sequence interface,two secondary sequence interfaces and five third-order sequence interfaces were identified.The single well sedimentary cycle characteristics were analyzed and the sequence internals were divided.HST(high system domain)and TST(transgressive system domain),in order to establish a sequence stratigraphic framework of the whole work area,on the basis of which two types of sequence deposition filling modes are proposed: limited platform deposition filling mode and open platform-stage Edge-slope-basin sedimentary filling model.The main controlling factors of tectonic subsidence,sea level rise and fall and paleoclimate are analyzed.According to the characteristics of seismic attributes,it is considered that the seismic facies of the study area can be divided into strong amplitude continuity,strong amplitude weak continuous,medium amplitude continuity,weak amplitude medium-weak.Continuously,according to the seismic configuration features,it is divided into pre-product,mound,parallel,messy,divergent,mound-heavy reflection and other major types.The platform is mainly composed of parallel parallel and sub-parallel structures as the main seismic reflection characteristics,and the platform edge region develops the characteristics of the hilly shape-internal chaos.The TST(transgressive system domain)is mainly characterized by a parallel parallel-sub-parallel structure,a medium-strong amplitude,and good continuity.The HST(high-level system domain)is dominated by a sub-parallel medium-weak amplitude and weak continuity feature.According to the analysis of single well sedimentary facies and the transition from seismic facies to sedimentary facies,the main types of sedimentary facies in the study area are identified: limited platform,open platform,platform margin,slope,basin,5 phases,7 subfacies and 11 sediments.The microfacies type is used to analyze the distribution characteristics of the sedimentary facies in the horizontal and vertical directions.The carbonate sedimentary model is established.The correlation between the three-dimensional reef-shoal sedimentary facies and various seismic attributes,horizon thickness and seismic facies is discussed.relationship.