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鄂尔多斯盆地中生界隐蔽性油气藏包括两种类型：三叠系延长组三角洲油藏和侏罗系延安组古地貌油藏。三角洲生、储、盖成油地质格架是形成第一种类型油藏的有利地质条件，半深湖相暗色泥岩为伸入到生油区的三角洲沉积体提供了油源，三角洲河道、河口坝砂体是油气聚集的重要场所，储油砂体上倾方向岩性变致密成为遮挡；第二种类型油藏形成主要受控前侏罗系古地貌形态，深切延长组的古河谷是油气运移的主要通道，古地形高部位是油气运移的指向，其上形成的砂岩局部压实构造成为油气富集场所。

SUBTLE RESERVOIR FORMATION LAW OF MESOZOIC IN E’ERDUOSI BASIN

There are two kinds of subtle reservoirs of Mesozoic in E’erduosi Basin,i.e.the delta reservoirs of Yanchang Formation,Triassic and the paleogeomorphological reservoirs of Yan’an Formation,Jurassic.The geologic framework of deltaic source reservoir seal was the beneficial geologic condition of forming the first kind of reservoirs,the dark mudstones of semideep lacustrine facies providing the oil source for the delta sediments extending to the oil generating area,the sandbodies of delta channel and debouch bar being the important places of accumulating oil and gas and the compactification of updip direction top of the reservoir sandbody becoming a seal.The formation of the second kind of reservoirs was mainly controlled by pre Jurassic paleogeomorphological shapes,the ancient river valleys deeply cutting in Yanchang Formation being the main pathways of oil/gas migration,the higher portions of terrain configuration being the target areas of oil/gas migration and the local sandstone compaction structures formed on the higher portions becoming the places of enriching oil and gas.