Based on Vail sequence stratigraphic theory and analysis of seismic and logging information, the sequence in the Paleogene Liushagang and Weizhou formations in the Weixi'nan Sag is classified, the strata framework of sequence is defined and established, the characteristics of sequence structure are analyzed and the distribution of non-structural traps is revealed. One first-order sequence boundary, two second-order sequence boundaries, eight third-order sequence boundaries and ten third-order sequences are identified in the Liushagang and Weizhou formations. According to the characteristics of sequence boundary structure, the third-order sequence boundaries can be divided into three types: type Tl, type T2, and type T3. And according to the characteristics of sequence stratigraphic structure, the ten third-order sequences can be classified into four types: one-divided sequence, two-divided sequence, three-divided sequence, and four-divided sequence. The favorable areas for the development of stratigraphic overlap traps are above type Tl and type T3 sequence boundaries, while the unconformity barrier traps are developed below type T2 and type T3 sequence boundaries. The favorable development periods of lithologic traps are the early period of three-divided sequence and four-divided sequence and the late period of two-divided sequence and four-divided sequence.%运用Vail层序地层学理论,综合利用地震、测井、录井等资料,对涠西南凹陷古近系流沙港组和涠洲组进行层序地层划分,建立层序地层格架,分析层序结构特征及非构造圈闭的发育规律.在该地区共识别出1个一级层序界面、2个二级层序界面和8个三级层序界面,划分出10个三级层序.依据层序界面结构特征,将层序界面分为T1型、T2型和T3型3种类型；依据层序地层结构特征,将10个三级层序分为一分层序、二分层序、三分层序和四分层序4种类型.T1型和T3型层序界面之上有利于发育地层超覆不整合圈闭,T2型和T3型层序界面之下有利于发育不整合遮挡圈闭,三分和四分层序早期及二分和四分层序晚期有利于发育岩性圈闭.
展开▼
