鄂尔多斯盆地含油气系统划分及特征

根据含油气系统的基本方法,鄂尔多斯盆地可以划出4个简单的含油气系统,即:中生界含油气系统和上古生界含气系统是已知的简单含油(气)系统(！);下古生界含气系统和侏罗系假想的简单含油气系统(·)。由于盆地内局部存在油气混源现象,尚存在一个复杂的含油气系统——奥陶系顶古风化壳复杂含气系统(！)。5个含油气系统的关键时刻趋于一致,盆地含油气系统具有多源、多灶单期成藏的特点。油气运聚单元的划分有利于认识盆地内油气的分布聚集规律。研究表明,河流-三角洲(渗)砂体是有利的油气运移通道(疏导体)和聚集带,砂体之间的滨浅湖或河流间湾泥岩构成岩性遮挡。根据油气运移分隔槽、疏导体及隔挡条件,可将上古生界含气系统划分为4个油气运聚单元;中生界含气系统划分为13个油气运聚单元,其中上三叠统延长组分为8个油气运聚单元;侏罗系下部(富县组、延安组延10、延9)划分为5个油气运聚单元。

Division and Distribution of Petroleum System in Ordos Basin.

According to standard of the traditional petroleumsystem, there are two known petroleum systems andtwo hypothetical systems in Ordos basin-Mesozoicpetroleum system(!), Upper Paleozoic petroleum sys-tem(!), Jurassic and Lower Paleozoic hypotheticalpetroleum systems(.). But there exists another thecomplex known petroleum system(!), which havetwo source rocks-Lower Paleozoic oil-type gas andUpper Paleozoic coal-type gas. Five petroleum sys-tems have roughly the same critical moment-lowerCretaceous. The direction and path of oil-gas migra-tion and the advantapeous reservoir is the main factorof controlling oil-gas accumulation. According to thedirection of oil-gas migration, conveyer and sealingconditions, the unit of oil-gas migration and accumu-lation can be divided.