鄂尔多斯盆地吴旗油区早侏罗世古地貌特征与油气富集关系

Palaeogeomorphological features and their bearings on the hydrocarbon accumulation in the Wuqi oil field, Ordos Basin during the Lower Jurassic

沉积时期的古地形、古地貌是控制沉积相发育与分布的一个重要因素,其在一定程度上也控制着后期油气圈闭的类型与分布。通过补偿印模法恢复了吴旗油区前侏罗纪古地貌形态,确定局部构造特征,开展有利储集相带预测。研究区油藏分布主要受控于古地貌形态,深切延长组的古河谷是油气运移的主要通道,古地形高部位为油气运移的主要方向,古河谷附近的砂体为油气富集的有利场所,上覆的沼泽相泥岩形成了良好的岩性遮挡条件。

The palaeogeomorphological features during the depositional periods are interpreted as important factors to control the development and distribution of sedimentary facies,and to a certain extent,to control the types and distribution of oil traps in the Wuqi oil field,Ordos Basin.In this study,the compensation impression method is employed to reconstruct the pre-Jurassic palaeogeomorphological features,clarify the local structural features,and predict the favourable reservoir facies zones.The palaeogeomorphological features controlling the distribution of oil pools in the study area include the palaeovalleys incised into the Yanchang Formation as main channels for the migration of hydrocarbons; topographic highs as the main direction for the migration of hydrocarbons; the sandstones along the palaeovalleys as the favourable localitites for the accumulation of hydrocarbons,and the overlying marsh mudstones as good lithologic barrier.