Characteristics Of The Carbonate Shoal Of Ordovician Yingshan Formation In Tahe Area, Tarim Basin

Based on the geologic survey study and analysis of outcrop profiles, well drilling/logging/core data, hundreds of outcrop and core samples slices and geochemical data, and the geologica seismic interpretation, and combined the pre-study achievement, the sedimentary characteristics of carbonate shoals of Cambrian-Ordovician in the Tahe area has been studied.The research work has made clear that the Tahe area has conditions to develop carbonate shoals, and that two types carbonate shoals have been developed, which are intraclastic shoals and bioclastic shoalsThe geological and geophysical response characteristics of carbonate shoals from microfacies to macroscopic features have been conclude based on the thin sectionscore rocks-well drilling/logging-seismic-outcrops data. The intraclastic shoals develop from the early Ordovician, and the intraclastic shoals developed like a layer cake with the thin layer and thick layer two patterns; The bioclastic shoals can be finded in TS1 well and TS2 well, and the echinoderm fragments are the main components, and the grains are cemented by sparry calcite, the echinoderm fragments diameter is big. All the two types shoals are deposited in periods, and each period shoal is corresponding to one high frequency cycle period, and the shoal are developed in the middle to late part of the high frequency cycle period.Three depositional stackying patterns of the carbonate shoals have been founded,including: Algae-Reef-shoal Interbed, Thick-Layer Cake Aggradation shoal, and Thin-Layer Cake Retrogradation shoal.It has been discussed and verified that the sea level change, the platform margin structure are the important controlling factors for the carbonate shoals development from Cambrian to Ordovician. The main control factors of particles beach, for high quality particle beach distribution prediction in tahe area.