Western Sichuan Depression The Middle Triassic To Be Two To Be Three Segments Of Sequence Stratigraphy And Sedimentary Facies

The author makes the systematical and complete sequence stratigraphy and sedimentary facies research to the Upper Triassic Series T₃x² and T₃x³ in the middle part of west Sichuan depression on the basis of outcrop, drilling, logging well and seismic data. Build up the district sequence stratigraphic framework, and divide T₃x² and T₃x³ into two long-term(LSC₃-LSC₄), ten middle-term (MSC₇-MSC₁₆) and Several tens short-term cycle; In the study area, the author denominate the lake and delta facies, and build up sedimentary facies model of the T₃x² and T₃x³. Finally, the advantageous reservoir facies and horizon have been predicted on the above mentioned study foundation. Between T₃x² and T₃x³ , T₃x² have more reservoir sandstone, and the channel region of delta frontal is the best reservoir facies, the bottom of middle base-level upper half-cycles and the top of middle base-level dropping half-cycles is advantageous reservoir horizon.