渤海湾盆地东营凹陷烃源岩碳氧同位素组成及地质意义

发布时间：2018-04-18 09:18

本文选题：碳氧同位素 + 闭流湖　；参考：《石油实验地质》2017年02期

【摘要】：对渤海湾盆地东营凹陷沙河街组烃源岩层段开展了系统取样和碳酸盐碳氧同位素分析,并结合文献中的数据资料,在层位精细划分基础上,系统总结了碳氧同位素组成特征及纵向的差异,并探索分析了古湖泊环境的演变过程。沙四段下亚段δ~(13)C和δ~(18)O呈现较好的正相关,指示了断陷初始期盆地封闭性水文地质条件,但其碳氧同位素又整体相对较轻,并且具有从下部向上部逐渐变重的特征,表明盐湖水体不稳定并受到不同程度的淡水影响作用。沙四段上亚段δ~(13)C和δ~(18)O整体呈现较好的正相关且明显加重,指示了断陷加速期咸化湖泊水体环境较为稳定和封闭的特征。沙三段下亚段不同岩性碳酸盐碳氧同位素存在一定差异,其中较好反映烃源岩原始碳氧同位素组成特征的非钙片页岩,其δ~(13)C和δ~(18)O值分布非常集中,指示断陷鼎盛期非常稳定、封闭的半咸化湖泊环境。沙三段中亚段与沙三段下亚段非钙片泥岩数据较为接近,从一定程度上继承了沙三下亚段沉积期湖泊水体的碳氧同位素特征。
[Abstract]:Systematic sampling and carbonate carbon-oxygen isotope analysis were carried out on the source rock of Shahejie formation in Dongying depression, Bohai Bay Basin.The carbon and oxygen isotopic composition characteristics and longitudinal differences are summarized systematically and the evolution process of paleo-lake environment is explored and analyzed.There is a good positive correlation between 未 ~ (13) ~ (13) C and 未 ~ (18) O in the lower submember of Sha 4, indicating the closed hydrogeological conditions of the basin during the initial period of the fault depression, but its carbon and oxygen isotopes are relatively light and gradually heavier from the lower part to the upper part.The results show that salt lake water is unstable and affected by fresh water to varying degrees.In the upper submember of the fourth member of the Shahejie formation, 未 ~ (13) C and 未 ~ (18) O are positively correlated and obviously aggravated, indicating the stable and closed water environment of the saline lake during the accelerated period of fault depression.There are some differences in carbonates carbon and oxygen isotopes among different lithologic carbonates in the lower member of the third member of the Shahejie formation, among which the non-calcareous shale, which reflects the characteristics of the original carbon and oxygen isotopic compositions of the source rocks, has a very concentrated distribution of 未 ~ (13) ~ (13) C and 未 ~ (18) O, indicating that the faulting is very stable at its peak.A closed, brackish lake environment.The non-calcareous mudstone data of the middle part of the third member and the lower part of the third member of the third member are close to each other, and the carbon and oxygen isotopic characteristics of the lake water during the sedimentary period of the lower member of the third member of the formation are inherited to some extent.
【作者单位】：中国石化胜利油田分公司勘探开发研究院;
【基金】：国家科技重大专项(2016ZX05006-001) 国家自然科学基金(41072096)资助
【分类号】：P618.13

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