利用野外露头、岩心、测／录井及地震解释等资料和手段，对四川盆地川西坳陷中段须四段层序结构特征进行研究。须四段为一个三级层序，可进一步划分出低位体系域、湖侵体系域和高位体系域，建立了等时层序地层格架，阐明其内部主要发育冲积扇—冲积平原—三角洲—湖泊沉积体系；依据层序地层结构特征，划分出非对称A1型、非对称A2型和对称型3种类型，其中A1型发育在龙门山山前地区，A2型主要发育在中江—洛带地区，对称型主要发育在龙门山山前地区和中江—洛带地区之间的过渡凹陷区；非对称A2型及对称型层序低位体系域和高位体系域是研究区优质储层的有利发育区。%The sequence characteristics of the fourth member of Xujiahe Formation in the middle area of Western Sichuan Depression have been studied by using outcrop, core, logging and seismic data. The fourth member of Xu⁃jiahe Formation is a three⁃order sequence and was divided into lowstand system tract, transgressive system tract and highstand system tract. An isochronous sequence stratigraphic framework was established, and its internal sedimen⁃tary characteristics were clarified, mainly developing an alluvial fan-alluvial plain-delta-lacustrine depositional system. The sequence was divided into three types based on depositional settings:symmetrical type, asymmetrical type A1 and A2. Type A1 developed in the piedmont region before the Longmen Mountain, the type A2 mainly developed in Zhongjiang-Luodai area, and the symmetrical type mainly developed in the piedmont region before the Longmen Mountain and the depression between Zhongjiang and Luodai. LST and HST of the asymmetric type and symmetric type A2 sequence were advantageous for the development of high⁃quality reservoirs.
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