Abstract:

Based on the outcrops, cores and well logs, strata in the Late Palaeozoic of Ih Ju Meng area in Ordos Basin are divided into zones by using sequence stratigraphy analysis of the Late Carboniferous and base level cycle analysis of the Permian. There are six types of sedimentary systems, including tidal flat, fan delta, shallow water delta developed during Taiyuan Age, alluvial fan developed during Permian, meandering river developed during Shanxi and late Shihezi Age, and braided river developed during early Shihezi Age. The main sandstone body for oil storage is constructed by distributary channel filling, subaqueous distributary channel filling of fan delta and shallow water delta, braided channel filling of alluvial fan, longitudinal bar of braided river, point bar, crevasse, and levee of meandering river. The authors also suggest that the lithofacies palaeogeography of the Late Palaeozoic of the study area, controlled by tectonicetting and the resultant slope, is dominated by fan delta and alluvial fans in the west, and by shallow water delta, meandering rivers, and braided rivers in the east

摘要：

依据露头、岩心、测井及地震等资料并运用层序地层学分析及基准面旋回分析等手段，对本区地层进行了小层划分与对比，首次将地层划分到岩性段。在此基础上，将研究区置于构造及其控制的海侵[CD*1/2]海退旋回背景下，运用比较沉积学理论，总结出本区晚古生代发育有潮坪、扇三角洲、浅水三角洲、冲积扇、辫状河和曲流河6种沉积体系及一系列亚微相；提出9种构成储集砂体的重要成因类型，并阐述了其形成条件、发育特征和识别标志。对不同时期岩相古地理研究表明，本区处于伊克昭盟隆起南坡，在北高南低及西陡东缓的古地形控制下，北或北北东向水系继承性发育，西部以形成扇三角洲（太原组）和冲积扇（山西组—上石盒子组）沉积为主，而东部则以形成浅水三角洲（太原组）、辫状河（下石盒子组）、曲流河（山西组、上石盒子组）沉积为主。