Weibei Oilfield is one of new oil‐bearing blocks in southern Ordos Basin in the recent two years .Taking 33 Oil Formation of the fourth member of Yanchang Formation in dense well area as the example ,based on various data including cores ,well logging and production performance ,internal configuration of underwater distributary channel sand of braided river delta is studied in this paper .Under the premise of the basic characteristics of single channel in single well ,using the method of well‐seismic tie in profile and the combination of the maximum thickness of single sand body and number of the sand bodies in each small layer in plane ,eight single channel development periods have been identified in Chang 33 Oil Formation ;the number and distribution of single channels in complex channels have been identified in plane as while;besides ,four kinds of sand bodies superimposition models and their distribution were summarized including incised superimposition model ,in‐completed incised superimposition model ,isolated model and thin‐layer superimposition model ,which provides geological basis for waterflooding in dense well area and the selection of future favorable area in its adjacent region .%渭北油田是鄂尔多斯盆地南部最近两年新发现的含油区块，本文以其密井网区延长组四段33油组为例，应用岩心、测井、地震及动态等资料，对辫状河三角洲水下分流河道砂体内部构型开展了系统研究。在分析单河道基本发育特征的基础上，剖面上井震结合识别单河道，平面上采用最大单层厚度与砂体层数交绘的方法，在密井网区长33油组识别出八个单河道发育期，单河道宽度一般在500～800m之间，宽厚比介于100～130之间；在平面复合河道中识别出单河道发育条数及分布范围；同时提出长33油组河道内部发育下切叠加式、不完全下切式、孤立式及薄层叠加式四种砂体叠置方式，明确了不同叠置模式在密井网区分布范围，为渭北油田密井网区注水开发和外围有利区带选取提供了地质依据。
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