鄂尔多斯盆地姬塬油田长8油层组岩性油藏特征

Characteristics of Lithologic Reservoir of Interval 8 of Yanchang Formation in Jiyuan Oilfield of Ordos Basin

姬塬地区长8油层组主要发育典型的浅水三角洲沉积。以高分辨率层序地层学分析为指导,对姬塬地区长8油层组进行了精细地层对比和小层砂体的划分,在此基础上编绘出长8油层组顶面构造图及等时条件下小层砂体的平面展布图。编图发现,研究区长8顶面为具多个鼻状隆起的西倾单斜,油层的发育多与鼻状构造有关,长8油层组主要发育岩性油藏。自身具备良好生烃能力并紧邻长7油层组优质烃源岩、稳定的三角洲砂体、西倾单斜及鼻状隆起的构造背景是长8油层组形成岩性油藏的必要条件,长8油层组下部地层较上部地层、研究区西部较东部更容易形成岩性油藏,同时西部储层明显优于东部储层。

The sedimentary rocks in Jiyuan Oilfield,Ordos Basin consists mainly of shallow-water deltas and shallow lacustrine facies.Based on the theory and technology of the high-resolution sequence stratigraphy,this paper makes a fine correlation of the strata of interval 8 of Yanchang Formation in Jiyuan and the splitting of small sandbodies.According to the strata correlation and sandbody splitting,a map is made of the top structure and isochronous distribution of small sandbodies of interval 8 of Yanchang Formation.The result indicates that the top structure of this interval is a west-dipping monocline,where the development of reservoirs is closely related to many nose-like structures.The close position to the source rocks of interval 7 of Yanchang Formation,its own good hydrocarbon-generating ability and the development of steady sand bodies and nosing structures on the west inclining monocline are all the necessary conditions for the lithologic reservoir formation in interval 8 of Yanchang Formation.The strata of below this interval and the west of the study area are favorable for the lithologic reservoir formation.Meanwhile,the reservoir of the west is better than that in the east of the study area.