Tarim Basin, Permian Sequence Stratigraphy

Plenty of petroleum is enriched in Tarim basin, and industrial oil flow has been found in Cambrian System, Carboniferous System, Triassic System, Jurassic System,Paleogene System and Neogene System, but petroleum exploration has not broken through in Permian System because of lower study level of sedimentary facies, reservoir and petroleum geology. The paper, which has studied geological setting, sequence stratigraphy and sedimentary feature, is guided by primary theories of sedimentary rock and sequence stratigraphy, integrated with seismic data and logging data, and the paper has evaluated favorable exploration area objectively in Permian System.Lithology, sedimentary structures,paleontology and logging data have been comprehensively study in the paper, and it can be gotten that facies comprise marine facies and continental facies and thick volcanic rock in Permian System.The facies can be divided into carbonate platform, fluvial,lacustrine,delta, which can be subdivided into 12 subfacies.Six sequence boundaries can be recognized in Bachu and Tazhong area in Tarim basin in Permian System, based on logging and outcrop data.Except B4 boundary belongs to typeⅡ,the others are typeⅠ,with the feature of incised channels.According to 6 sequence boundaries,5 third-order sequences can be divided in Permian System, and all of sequences correspond with classical sequence stratigraphy pattern of Vail. Statistic data gotten by interpretation of logging data show that average porosity of clastic rock ranges from 6% to 8%,and average permeability is 0.06×10-3μm2,so physical property of clastic rock is poorer, which belongs to middle to poor reservoir. Nanzha formation distributes mainly in southwestern Tarim basin, with reservoirs rock types including dolomite and grain carbonate.Physical property of dolomite presents well, but grain carbonate property doesn't present well.The two kinds of reservoir can be recognized as good.Based on study, the best reservoir distributes around area of well Zecan 1,and typeⅡreservoir distributes fringe of Zecan 1.typeⅢreservoir distributes mainly on Maigaiti slope and Qukuqiake structural zone,what's more, typeⅢreservoir also distributes on Mazhatage structure belt and northern area of well Hetian 1 to well He 4.