关键词: 复合砂体构型, 点坝, 决口扇, 废弃河道, 曲流河沉积, 基准面旋回, 明化镇组, 新近系, 秦皇岛32-6油田

Abstract: Through logging，dominant seismic attribute fusion， spectrum attribute trend analysis and other methods， the reservoir architecture characteristics of the composite sand bodies in the second oil group（NmⅡ）of the lower Minghuazhen Formation of Neogene in northern Qinhuangdao 32-6 oilfield were studied，and the control effect of base-level cycle on the composite sand body architecture was clarified. The results shows that： （1）The composite sand bodies of the NmⅡ in northern Qinhuangdao 32-6 oilfield are mainly point bar and crevasse splay deposits，and the seepage barrier is mainly floodplain and abandoned channel deposits. According to logging facies and sand body structure rhythm，the internal structure of composite sand bodies is divided into box shape in the head and middle of point bar，bell shape in the end of point bar，funnel shape in crevasse splay，peak shape and low-amplitude tooth shape in floodplain and abandoned channel. The external stacking patterns of the composite sand bodies include isolated type，tight lateral stacking type，scattered lateral stacking type and stacking type. （2）In the early stage of NmⅡ，the intertwined channel mainly deposited point bar and crevasse splay. Sand bodies of tight side-stacking type and stacking type were widely developed. In the late stage of NmⅡ，the channel evolved into single band shape，and the crevasse splay was sporadically distributed on the convex bank of the channel. The scale of the composite sand bodies became smaller，mainly scattered lateral stacking type and isolated type，and the floodplain and abandoned channel became the seepage barrier between the composite sand bodies. （3）In long-term to middle-term cycles in the study area，heterocyclic factors such as tectonic activities affect the external morphology and stacking of composite sand bodies by adjusting the accommodation space and sediment supply，while in short-term cycles， the internal structure of sand bodies is affected by autogenetic cycle such as sediment types and hydrodynamics.

Key words: composite sand body architecture, point bar, crevasse splay, abandoned channel, meandering river deposits, based-level cycle, Minghuazhen Formation, Neogene, Qinhuangdao 32-6 oilfield