Research On Sequence Stratigraphic And Sedimentary Facies Of Ordovician Yingshan Formation In Tahe Area,Tarim Basin

By making full use of outcrop, drilling, logging, seismic, laboratory analysis and other data, sequence stratigraphy, depositional systems, sedimentary environment evolution of Ordovician Yingshan Formation in Tahe area are studied deeply and systematically. Based on a detailed and summary research of the previous research,the paper had a preliminary understanding of tectonic setting of the Tahe area.Firstly the paper identified the lower level unconformity. Based on the outcrops,drilling logging data of Yingshan formation of lower level of Yingshan Formation in Tahe area by studing the features of outcrop, drilling, logging data. On a boundary of this, the paper divide the Yingshan Formation into four forth-order, named Y1, Y2, Y3,Y4 segment, and made a conclution of the superposition pattern of subsequebce,finding Yingshan Formation mainly composed by transgressive system tract(TST)and highstand system tract(HST). At the same time start horizon tracing of Yingshan Formation, and established the sequence stratigraphic framework.In Yingshan formation the paper main recognized nine kinds of seismic phase,which strong amplitude seismic phase attributes by tectonic reworking influence.According to the detailed research on 3D seismic data of Tahe Area in middle to weak amplitude seismic phase, the paper identified a variety of structural types such as left forward progradational reflection, right forward progradational reflection, moundy reflection. Progradational reflection mainly developed in margin of platform facies,showing the high energy environment, and the parallel reflection showing the low energy environment.Based on the reseach of seismic facies and the distribution of reflection structure,the paper identified two types of seismic facies of restricted platform and open platform face in Yingshan formation. And finding that early in the western part of Tahe area mainly develop restricted platform facies, contrarily in easterm part developed open platform facies, latter the water rised, the whole area developed open platform facies. There are two sedimentary microfacies in restricted platform facies and open platform facies, the interbank sea facies developed in the midlands andintra-platform facies developed in the peripheral areas.Through the reseach of distribution of microfacies as well as the evolution of sediment of Yingshan formation in Tahe area, we can see that in Yingshan formation period, the whole area was composed by transgressive system tract(TST) and highstand system tract(HST), the water rised up during the Y1,Y2,Y3 period, slightly dropped down in Y4 period, and the shelf was on the east side of Tahe area.