鄂尔多斯盆地延长组长7沉积环境及沉积类型

Depositional Environments and Sedimentary Types of Chang7 Reservoirs of Yanchang Formation, Ordos Basin

鄂尔多斯盆地长7油层组沉积主要为半深湖-深湖沉积环境。沉积相类型以浊积扇砂体为主，砂体厚度大、连片性好、分布面积大，平面上主要分布于陇东地区；其次为三角洲前缘砂体，砂体多呈条带状分布，局部发育分流河道分叉交汇叠加的连片性好、规模较大的有利储集体，平面上主要分布于陕北地区水体较浅的沉积区。长7油层组为典型的“源储共生、自生自储”成藏组合，具形成致密油的有利地质条件，勘探潜力大。

The deposition of Chang7 reservoir group of Ordos basin is mainly semi-deep lake and deep lake de- positional environment. Types of sedimentary facies are mainly turbidite fan sand bodies, with big thickness, linking-up well together, and a large distribution area, mainly distributed in the Eastern Gansu （Longdong） area; secondarily the delta front sandstone body, with mostly strip-shaped distribution, and well linked-up large-scale favorable reservoir bodies were locally developed in the distributary channels with bifurcated intersection and su- perposition, mainly distributed in shallow water deposition area in Northern Shaanxi area. The Chang7 reservoir group is a typical reservoir array of ＂source-reservoir paragenesis, authigene and self-reserving＂, with favorable geological conditions of tight oil reservoirs, and good potential for exploration.