The Character Of Cretaceous Sequence Stratigraphy And Depositional System At Th12307-th12116 In The Tahe Oilfield, Xinjiang

For the exploration of Tahe oilfield, we focused on the Ordovician, the Carboniferous and Triassic, and ignored the Cretaceous research at past. But this paper which based on the theories of continental sequence stratigraphy and sedimentology, examines the sedimentary system, sequence stratigraphy, lithofacies paleogeography of Cretaceous Formation at the TH12307 - TH12116 area in Tahe oilfield by using geologic, sesmic and logging methods. On the basis of previous research on this study, we do a lot of study on the cretaceous stratum division and contrast by petrological characteristics, well logging, paleontology, geochemical data. At the same time, we found that the lower Cretaceous(K1), was composed of Yageliemu Formation, Sushanhe Formation, Baxigai Formation and Bashijiqike Formation. Using methods of the high-resolution sequence stratigraphy, and combining seismic stratigraphy analysis, we divided the Cretaceous Formation into three super long-term, six long-term and sixteen medium-term sequences cycle, meanwhile, we establishs sequence stratigraphic framework of the Cretaceous Formation in study area and also deeply investigates the characteristics of all levels sequence by seismic comprehensive analysis method. According to the integrative analysis of regional tectonic, sedimentary background, the field of outcrop, core observation, and combined with various wells and seimic data, this paper divided the sedimentary system of lower Cretaceous at study area into three types, mainly including meandering delta, braided delta, lacustrine facies. Braided delta mainly distributed in Yageliemu Formation, Baxigai Formation and Bashijiqike Formation, but Sushanhe Formation is consisted of delta front and shallow lacustrine facies. Meanwhile, it deeply discussed the characteristics of sedimentary facies, subfacies and microfacies, and established the sedimentary mode of Cretaceous in study area. Finally, by means of seismic attributes, this paper have finished the sedimentary facies maps of every systems tract within the sequence straigraphic framework of study area, and described characteristics and evolution of every sequence cycle in detail, adopting super long-term sequence cycle as basic mapping unit.