Sequence Stratigraphy? Sedimentary Evolution And Its Controlling Factors Of Upper Devonian -Carboniferous In The South Slope Of The Tabei Uplift

Tabei uplift is a sub-structural unit of the Tarim basin and has abundant hydrocarbon resources, which lies in the north of Tarim basin.Tabei uplift goes through multiple phases of structural activity and forms many sets of oil source rocks and reservoir-seal assemblages in the long geological history. It has very good conditions for hydrocarbon accumulation.The marine sandstone of Upper Devonian–Carboniferous distributes widely and has good reservoir quality. It is one of the main exploration targets in the south slope of Tabei uplift. When the structural traps in the Tabei uplift become less and less, more and more attention is paied to the stratigraphic traps. During the Palaeozoic, Tabei uplift is a uplift and it has good conditions to form the stratigraphic traps. In this paper, the theories of sequence startigraphy, sedimentology and seismic sedimentology were used to study the sequence stratigraphic framework, depositional system distribution and their controlling factors of Upper Devonian–Carboniferous in Tabei uplife, combined with cores, well logs, outcrops and seismic datas. The study can provides envidence for the exploration of stratigraphic traps.Two second-order and three third-order sequence boundries were recongnized in the Upper Devonian–Carboniferous. Thus the Upper Devonian–Carboniferous can be divided into one second-order sequence and four third-order sequence. TST and HST were found in the SQ1, SQ3 and SQ4 sequence , SQ2 has LST besides TST and HST.According to cores, well logs and seismic datas, several depostional systems were recognized. They are beach depositional system, wave-controlled delta depositional system, lagoon-tidal-flat depositional system, braid river delta depositional system, fan delta depositinal system, restricted platform depositional system and mixture shore depositional system.Fisher plot was used to study the relative sea level change of Tabei uplift. The relative sea level change of the study area is very similar to the global relative sea level change. It reveals that the global relative sea level change controls the form of sequence and distribution of depositional system. The paleogeomorphology of SQ1 and SQ2 sequence was reconstructed. The paleogeomorphology have impact on the distribution and evalution of depositional systems.The main heavy mineral in the Upper Devonian–Carboniferous of Tabei uplife were hematite, leucoxene, zircon, tourmaline. They are stable heavy mineral assemblages and reveal that the matter source came from the continent eroded source rocks.After analysis of the typical oil traps, Saike structure, south area of HADE, Hd4 and Ha6 borefield were thought to be favorable belt for exploration based on the sequence stratigraphic framework and distribution of depositional systems.