The Study On The Sedimentary And Sequence Stratigraphy Characteristics And Source-reservoir-caprock Assemblages Of The Triassic At The Tabei-tazhong Area, Tarim Basin

Based on the theory of sedimentology, sequence stratigraphy and petroleum geology, this dissertation take the Triassic strata as the object,systematically research the depositional system, sequence stratigraphy and prediction of favorable block. These achievements would provide important basic information for further petroleum exploration in the basin.Based on the signs of cores, log respons e and combination of phase sequence, the Tabei-Tazhong area identified a total of 5 classes depositional systems and 26 microfacies in the Triassic. Mainly developed the braided delta, fan delta and the sublacustrine fan depositional system. Consequently, the depositional models of the Triassic in the Tarim basin have been established, which Include depression basin gentle slope braided delta model, deep Water sublacustrine fan model and depression basin steep slope fan delta model.On the theoretical basis of classical sequence stratigraphy and nonmarine sequence stratigraphy,s new progression, the analysis of sequence is made in Tabei-Tazhong area from the recognition sequence boundary by use of 3-D seismic, drilling, logging and coring and analysis of laboratory data.Based on sedimentology, palaeontology, geophysics and geochemistry signs, five sequence boundaries were identified (SB1-S B5) . There are several nature of sequence boundaries, including unconformity, onlap-offlap surfaces,mutant form of surface of logging curve,conversion surface of cycles overlapping mode, erosional surfaces and transitional surfaces of different lithologies,which the erosional surfaces and transitional surfaces of different lithologies are most common.According to the key surfaces, it was the first time to divided Triassic into two second-order sequences(SSQ1,SSQ2)and 4 third- order sequences( SQ1-S Q4) in Tabei-Tazhong area.Each sequence developed lowstand systems tract(LST),transgressive systems tract(TST) and highstand systems tract (HST).Some of the cut erosion site is lack of HST and in some morphologic deep areas is lack of LST.Based on the lot of well data to be studied as well as the long sections tied with boreholes to be correlated, and combined with precise calibration of seismic profiles, the regional sequence stratigraphic framework has been established. The number of sequence development can better comparison in East-west study area,the upper part of sequence was missing because of local uplift and Tabei was missing the lower part of sedimentary sequence.The paper combined the filling process sequence with sequence development of the controlling factors and built two types of squence filling patterns in depression basin i.e. gentle slope sequence filling pattern and steep slope sequence filling pattern.In eastern and southeastern parts of the lake is a typical representative of the former.The after uplifted area of Tabei as a typical representative of latter.Based on the third sequence (long-term cycles) and the sedimentary system, It is the first time to choosing the rising and falling base-level phases of each third sequence as the isochronous mapping unit, and carried out thesequence-paleogeography maps of the Triassic in Tabei-Tazhong area. Systematic analysis of the sedimentary facies evolution of time and space law in Tarim Basin All of these,the paper analyzed the space-time configuration rule of reservoir rock in the systems tract, and then study source rock, reservoir rock and cap rock characteristics and the rule of combination development of spatial and temporal distribution. Finally, coupled with exploration fruits and distribution of lithological and stratigraphic traps in the Tabei area, proposed two favorable exploration blocks.