鄂尔多斯盆地延长组地层底面古构造定量化演化及其石油地质意义

为定量化明确延长组地层在几个关键沉积期的底面凹凸构造面貌特征，基于鄂尔多斯盆地大量钻井等资料并采用盆地模拟技术，划分4个地层单元，即长10～长8、长7、长6～长4+5和长3～长1,定量化考察延长期湖盆在各层地层单元沉积末期的底面古构造特征。结果表明：长8沉积期末，地层底面构造高程整体表现为“东高西低、南高北低”的特征，主湖盆范围的构造等高线在-600 m以下；长7地层沉积期末，整体表现为“南高北低”的古地貌特征，主湖盆范围主要分布在盆地北部、构造高程达-1 150 m以下；长4+5沉积期末，凹陷区分布在盆地西北区域、分布范围和构造高程差变小、约为200 m;长1沉积末期，地层底面构造面貌格局整体表现为“东高西低”的古地貌特征，地层底面凹凸构造高程差为300～400 m。各沉沉积期底面凹凸构造发育，缓坡构造面貌区域是油藏分布的有利区。

The bottom of Yanchang Formation in Ordos Basin Quantitative evolution of paleostructure and its petroleum geological significance

IIn order to quantify and define the features of the bottom concave and convex structure of the Yanchang Formation in several key sedimentary periods, four stratigraphic units, namelyChang 10~ Chang 8, Chang 7, Chang 6~ Chang 4+5andChang 3~ Chang 1, were dividedby basin simulation technology based on a large number of drilling data in the basin. The paleostructural featuresof the bottomof the lake basin in the Yanchangperiod at the end of the sedimentary periodof each stratigraphicunit were quantitatively investigated.The results show that at the end of the sedimentary period of Chang 8, the structural elevation of the bottom surface of the formation is "high in the east and low in the west, high in the south and low in the north", and the structural contour of the main lake basinis below -600m. At the end of the sedimentary period of Chang 7 formation, the paleogeomorphology was "high in the south and low in the north". The main lake basin was mainly distributed in the north of the basin, and the structural elevation was below -1150 m. At the end of the sedimentary period of Chang 4+5, the depression area was distributed in the northwest area of the basin, and the difference between the distribution range and the structural elevation became smaller, about 200 meters. At the end of Chang 1 deposition, the overall structural pattern of the bottom of the basin showed a paleogeomorphic feature of "high in the east and low in the west", and the elevation difference of the concave-convex structure of the bottom of the basin was about 300-400 meters. The structural features of gentle slope on the bottom of each sedimentation period are favorable areas for reservoir distribution.