东营凹陷深陷期层序特征及沉积充填模式

Sequence characteristics and sedimentary filling model in deep-faulted period of Dongy-ing depression.

形成于湖盆深断陷期的东营凹陷沙三段-沙二段下亚段可划分出三个深断陷型层序,三个层序结构相似,由低位体系域、湖扩展体系域和高位体系域组成。层序的主要特征是发育数量众多的低位扇砂体、区域分布的油页岩和深湖相泥岩及大型的进积三角洲砂体。层序纵向上叠加使盆地边缘形成明显的砂泥岩旋回性沉积,盆地中心主要为泥岩夹浊积砂岩。层序中发育的各类低位扇砂体、深水浊积砂体及三角洲前缘滑塌浊积砂体具有优越的成藏条件,是形成岩性油藏最有利的砂体类型。构造坡折带是控制各类砂体发育和分布的主要因素,构造坡折带附近是寻找岩性油藏的有利位置。

The strata from the lower second member to the third member of the Shahejie Formation in Dongying sag, formed in the basin deep-faulted period, can be divided into three deep-faulted sequences. The three sequences had the similar structure which was composed of low-stand systems tract, expanding systems tract and high-stand systems tract. The main characteristics of the sequences had lots of low-stand fans sand bodies, regionally distributed oil-shale and deep-lacustrine mudstone, and large progradational delta sand bodies in the sequences. Sand-shale cyclic sedimentation developed at margin of the basin formed by longitudinal stacking of the sequences and shale contained turbidite was at center of the basin. All sorts of low-stand fans sand bodies, deep-water turbidite sand bodies and delta front fluxoturbidite sand bodies developed in these sequences had the favourable reservoir-forming conditions and they were the best type of sand bodies forming lithologic oil reservoirs. Structural slope break belts were the dominant factors that control the development and distribution of each type of sand bodies, thereby they became the most favorable position to find lithol-ogic oil reservoir.