镇泾区块延长组层序格架内油层分布规律研究

OIL RESERVOIR DISTRIBUTION IN SEQUENCE FRAMEWORK OF YANCHANG FORMATION,ZHENJING BLOCK

延长组是鄂尔多斯盆地西南缘镇原-泾川区块的一个重要勘探层位。通过岩芯观察、测井资料、薄片研究、粒度分析等,对该区块长8、长6两套厚层砂岩进行详细的层序地层和沉积学研究。研究表明:长8厚层砂岩由水下分流河道砂体、河口坝砂体与水下分流河道砂体的混积体、坝顶席状砂与滑塌体叠置组成;而长6厚层砂岩是由薄层的河口坝砂体与厚层的水下分流河道砂体叠置而成。长8油层主要分布于高可容空间、高沉积物供给条件下,经过强的水动力淘洗的坝顶席状砂砂体中;而长6油层主要分布于低可容空间、高沉积物供给条件下,经过强的水动力淘洗的水下分流河道砂体中。

Yanchang Formation is an important exploring layer of Zhenyuan-Jingchuan Block in southwest Ordos basin.Research indicates that thick sandstones of Chang 8 Formation are composed of subaqueous distributary channel sandstones,mixtures of subaqueous distributary channel sandstones and mouth bar,sheet sandstones over mouth bar and slump sandstones,and thick sandstones of Chang 6 Formation are consisted of thin mouth bar sandstones and thick subaqueous distributary channel sandstones by analyzing sequence stratigraphy and sedimentology of two thick sandstones of Chang 8 and Chang 6 Formation based cores,well logs,slices and particle size analyzing.Only the sandstones called as sheet sandstones over mouth bar can enrich petroleum which formed under the background of high accomodation,high sediment supply and intense current in Chang 8 Formation.Relatively,petroleum enriches in subaqueous distributary channel sandstones which formed under the background of low accomodation,high sediment supply and intense current in Chang 6 Formation.