Study On Sequence Stratigraphy And Sedimentary Facies Of Paleogene In Southwest Tarim Basin

The study area of the paper is located in the southwest of Tarim Basin,including four tectonic units of Kashi depression,Shache uplift,Yecheng-Hetian depression and Mengaiti slope.The study aim of the paper is the Paleogene,which is divided into the Paleocene,Eocene and Oligocene,including the Tuilok formation,Aertashi formation,Qimugen formation,Kalataer formation,Wulagen formation,Bashibulake formation.According to the research content of this paper,with the guidance of the theory of multi-discipline,combined with the oversea and domestic research status of carbonate rocks and sequence stratigraphy,on the basis of careful analysis of the thin core,drilling?logging?geochemical and geophysical data,deeply research the purpose layer,Study on the relationship between rock types,sedimentary environments,sedimentary facies and sequence stratigraphy.The Paleogene in southwestern Tarim Basin is greatly affected by early Himalayan movement and late Himalayan movement.The early Himalayan movement occurred during the late Cretaceous,and the middle-late Himalayan orogeny occurred in the late Oligocene.In southwestern Tarim Basin Paleogene,in the early Paleogene to the late Eocene with the global sea-level rise,the climate is relatively humid,in the study area development the barrier coast and open platform,confined platform and evaporation platform depositional system controlled by salinity;in the late Eocene,due to the global sea level decline sea water withdrew from the southwest of the Tarim Basin,alluvial fan delta lacustrine sedimentary system is developed in the study areaThe change of marine-continental facies sedimentary environment of Paleogene in Southwest Tarim Basin,lead to a rich types of sedimentary facies.The Southwest of Tarim basin ontinental sedimentaryin developed the alluvial fan-delta-lacustrine depositional system,the marine sediments are developed with barrier shore and open platform,restricted platform and evaporation platform depositional system which controlled by seawater salinity.Base on the theories of sequence stratigraphy,combine with the sedimentary background,the rock strata,seismic stratigraphic of the study area,make a comprehensive analysis,identify two secondary order sequence interface SSB1?SSB2,and six erosion unconformity third order sequence interface SB2-SB7.On the basis of the research on well profile and the seismic facies,research on sedimentary facies distribution in sequence framework and its main control factors,establish sequence sedimentary evolution model in the study area.Finally compile the floor plan of sedimentary facies,and reveal the distribution rule of sedimentary facies.The main controlling factors of the formation of Paleogene sequence on the Southwest Tarim Basin are tectonic sbsidence,sea level change and ancient climate conditions.Tectonic movement controls sequence which is mainly embodied in the its influence on sequence interface and sedimentary paleogeomorphology;the rise and fall of sea level controls the formation of third order sequence interface and succession of systems tracts within sequence;The ancient climate change affect the change of carbonate platform type and location.Comprehensively analyze of the sedimentary,sequence stratigraphy and reservoir characteristics in the Southwest Tarim Basin,the main favorable reservoir facies belt is SQ4(Kalataer formation)the the open platform beach limestone and dolomite reservoir body.The reservoir space is mainly composed of secondary pores,include the intergranular(dissolved)pores,intragranular(dissolved)pores,biological framework pore and intergranular(dissolution)pore.