Analysis Of Sequence Stratigraphy And Reservoir In Ordovician Lianglitage In Tazhong No.1 Slope Break, Tarim Basin

It is based on carbonate sequence stratigraphy, sedimentology and geology theory in this paper. It uses the method of drilling and seismic analysis to analyze the Ordovician Lianglitage in Tazhong No.1 slope break,Tarim basin deeply. It divides the sequence, predicts the distribution of sedimentary facies and evaluate the favorable reservoir.We select more than 10 wells which containing Ordovician strata. It used the markers of exposed strata, sea-level changes and the change logging etc. to classify sequence. Therefore Lianglitage is divided into three sequences (Sq1~Sq3). Most representative wells in the study area are selected in order to conduct the correlation of sequence stratigraphy on the well profile, and the stratigraphic framework is established combined with seismic data.Using depositional models of carbonates, established by Tuker, Lianglitage Formation in Tazhong No.1 slope break can be recognized as rimmed continental shelf system. Basing on it, in combination with logging geology, sedimentology and research results of predecessors, four types of sedimentary facies can be recognized, that is organic reef, organic bank, lime mud mound and interbank sea. According to the logging and seismic data, spatial distribution of sedimentary facies can be predicted. Vertically, organic reef mainly developed in the middle and lower part of the transgression system tract, while organic bank developed at the bottom and interbank sea at the top; in addition, organic reef can be also encountered in the middle part of the high system tract and organic bank predominantly developed at the top. Horizontally, organic reef mainly distributed at the position nearest to the shelf break, showing longitudinal zonality; organic bank is widespread and mostly developed near the shelf break, and organic bank combining with organic reef developed in the northwest of the 24-26 well field in Tazhong, while only in the form of organic bank in the southern part; interbank sea widely distributed in the research area; lime mud mound mostly developed on the bulge of the sub-depression inside the terrace.Obviously, the development of organic reef and bank presents regional character, in connection with control factors of it. There are many factors controlling the development of organic reef and bank, such as sunlight, water temperature, salinity, palaeotectonics, eustatic level change and so on. In this dissertation, palaeotectonics, palaeogeomorphology and eustatic level change are analyzed, and the results can be obtained, that is, tectonic high advantages the growth of organic reef and bank, and stable eustatic level lay a foundation for the development of organic reef, when eustatic level changes rapidly, no reef developed.According to the establishment of sequence stratigraphic framework, the prediction of sedimentary facies distribution and the analysis of control factors of sedimentary facies, combining with the given well site (the wells having oil and gas shows in Lianglitage Formation), and analyzing tectonic and depositional factors comprehensively, reservoirs in well field 82, 24 and 26 are analyzed comprehensively and reservoirs in every well field are evaluated.