以沉积学和高分辨率层序地层学理论为指导，利用钻井、测井、岩心和地表剖面等资料对川中—川南过渡带须家河组二段进行高分辨率层序地层学研究。在不同级别基准面旋回层序界面和湖泛面的类型、性质、规模大小进行识别的基础上,将须家河组二段划分为3个中期基准面旋回层序（MSC）、8个短期基准面旋回层序(SSC)。在短期基准面旋回层序中进一步识别出向上“变深”的非对称型(A型)、向上“变深”复“变浅”的对称型（C型）2类旋回结构。指出最有利储集砂体形成于基准面旋回上升的早期和下降晚期。

Guided by the sedimentology and high\|resolution sequence stratigraphy theory, in combination with the data of outcrop profile, drilling core and well logging, this paper studied the high\|resolution sequence stratigraphy of the 2nd member of Xujiahe Formation in the middle and south Sichuan transitional zone. On the basis of recognition of the type, property and of different levels datum sequence interfaces and lake surface, Xujiahe Formation can be divided into 3 middle-term base level cyclical sequences (MSC) and 8 short\|term base level cyclical sequences (SSC). Among the short\|term base level cyclical sequences (SSC), we identified two cyclical structures, which are asymmetry form deepening upwards (A form)  and symmetric form deepening upwards then getting shallow again (C form). The studies show that the favorable reservoir sand were developed in the early time of the base-level cycle rise and the later time of its fall.