东营凹陷沙四中亚段盐湖相烃源岩研究

Investigation on the Salt Lake Source Rocks for Middle Shasi Column of Dongying Depression

东营凹陷下第三系沙河街组沙四中亚段蒸发岩十分发育 ,其中与泥岩共生的含盐系地层在胜坨南部及中央隆起带等地区厚逾千米。通过大量样品的分析测试和对这套蒸发岩沉积体系的研究 ,认为沙四中沉积时期湖盆充填呈现出欠补偿的饥饿状态 ,并建立了深水蒸发成盐的沉积模式。蒸发岩夹层中的深灰色泥岩和页岩的地球化学特征充分体现了盐湖沉积环境标志。高盐环境有利于有机质的富集和保存 ,沙四中亚段的灰色泥岩和页岩为东营凹陷的一套有效烃源岩。

Evaporite is well developed in the middle Shasi column of Shahejie Formation,Tertiary system in Dongying Depression,where the thickness of saliferous layers with mudstone exceeds 1000 m in the southern Shengtuo and central rift zone. Analysis of many samples and study on sedimentary system show that the lake basin was in an under-filling condition. A deep water evaporite formation model was established. The geochemical characteristics of dark gray mudstone and shale in evaporite layers record the sedimentary environment of salt lake. The high salt medium is beneficial to organic concentration and preservation. The gray mudstone and shale in middle Shasi column was a kind of high quality source rocks in Dongying Depression.