东营凹陷沙河街组四段孢粉相特征及其生烃潜力

Characteristics of palynofacies and its hydrocarbon generation potential of member 4 of Shahejie formation in Dongying depression

根据东营凹陷3个钻孔取心井沙河街组四段(Es4)烃源岩样品经过全封闭的孢粉学处理,探索沉积有机质的垂向变化,对深层沉积环境演变及生烃潜力进行研究。结果表明:东营凹陷Es4烃源岩自下而上可识别出3个孢粉相和两个亚相,孢粉相分别以木质组织、微粒状无定型和海绵状无定型优势为特征,亚相以孢型和木质组织丰度相区别;孢粉相的沉积环境分别为边缘浊积、扇三角洲发育的闭塞盐湖、持久分层闭塞超盐湖、封闭型季节分层半咸水深湖、封闭-开放型分层-混合半咸水较深湖,指示东营古湖泊水体逐步加深的沉积过程;随着淡水注入的增加,水体盐度逐步降低,湖泊生产率升高,有机质从以陆源输入为主逐渐过渡到以湖泊自身生产为主,有机质丰度逐步提高,烃源岩生烃潜力由较差到最好。

The source rock samples which were drilling cores from member 4 of Shahejie formation （ Es4 ） of Dongying de- pression underwent sporopollen processing in totally enclosed conditions. Based on this, the vertical sedimentary organics changes, the deep sedimentary environment evolution and the hydrocarbon generation potential were researched. The results show that the hydrocarbon source rocks of Es4 in Dongying depression are identified as three palynofacies and two sub-palyno- facies from bottom to up. Spores powder facies are charactered by woody tissue, particle amorphous and cavernous amorphous dominant position respectively, and sub-facies are distinguished by spores type and woody tissue abundance. The sedimentary environment of palynofacies includes edge turbidite, the occlusion salt lake developed in fan delta, the super occlusion salt lake of lasting layered, occlusion season layered half salt water deep lake and closed-open layered-half salt water mixed with deep lake, which indicates the sedimentary process of gradually deepen of ancient lake in Dongying. With the increase of wa- ter injection, water salinity gradually reduces and the productivity of lake increases. And the organic matter input varies from mainly by terrigenous supply to its own production in dominance. The organ!c matter abundance increases gradually and the hydrocarbon generation potential of source rocks varies from poor to the best.