东营凹陷沙河街组沙三下-沙四上亚段泥页岩岩相与沉积环境的响应关系

发布时间：2019-06-10 14:09

【摘要】：泥页岩的沉积环境控制了矿物、有机质特征和岩相类型。开展东营凹陷古近系沙河街组泥页岩薄片、X衍射、热解和微量元素等分析,研究各层段元素地球化学特征和岩相类型,探索沉积环境变化与岩相组合的响应关系。研究表明沙河街组沙三下-沙四上亚段泥页岩包含了均匀块状泥岩、细纹层状页岩、宽纹层状页岩、断续纹层状页岩和含石膏构造泥岩5种岩相类型。各层段沉积环境变化明显,沙四纯下次亚段沉积时期水体盐度最高,随着湖泊淡化,水体盐度降低,至沙三下亚段已演化为盐度较低且波动稳定的湖泊环境。岩石类型与沉积环境关系密切:沙四纯下次亚段浅水高盐度条件下沉积了石膏构造泥岩和少量均匀块状泥岩;沙四纯上底部高盐度水体加深的环境下沉积宽纹层页岩和少量细纹层页岩;沙四纯上次亚段上部盐度降低环境沉积均匀块状泥岩和少量宽纹层页岩;沙三下亚段深水安静且盐度较低的环境沉积细纹层页岩,充分展现了沉积环境对岩相的控制作用。因此,关注泥页岩沉积环境演变与岩相成因,探讨岩石与沉积环境响应关系,能够为非常规油气勘探提供新的思路。
[Abstract]:The sedimentary environment of shale controls minerals, organic matter characteristics and petrographic types. The shale flakes, X-ray diffraction, pyrolysis and trace elements of the Paleogene Shahejie formation in Dongying sag are analyzed, and the geochemical characteristics and lithofacies types of each member are studied, and the response relationship between the change of sedimentary environment and the assemblage of lithofacies is explored. The results show that the shale of Shahejie formation consists of five types of shale: uniform block mudstone, fine grain layered shale, wide grain layered shale, intermittent striated layered shale and gypsum bearing structural mudstone. The sedimentary environment of each member changed obviously, and the salinity of the water body decreased with the desalination of the lake, and evolved into a lake environment with low salinity and stable fluctuation. The rock type is closely related to the sedimentary environment: gypsum structural mudstone and a small amount of uniform massive mudstone were deposited under the condition of shallow water and high salinity in the next submember of Shasichun. The wide grain shale and a small amount of fine grain shale are deposited in the environment where the high salinity water body at the upper bottom of Sha 4 pure is deepened, and the uniform massive mudstone and a small amount of wide grain shale are deposited in the upper part of the last submember of Sha 4 pure. The sedimentary fine grain shale, which is quiet in deep water and low in salinity, fully shows the controlling effect of sedimentary environment on lithofacies in the lower member of Sha 3. Therefore, paying attention to the evolution of shale sedimentary environment and petrogenesis, and discussing the response relationship between rock and sedimentary environment can provide new ideas for unconventional oil and gas exploration.
【作者单位】：中石化胜利石油分公司勘探开发研究院;同济大学海洋地质国家重点实验室;
【基金】：国家自然科学基金项目(41672115) 国家油气重大专项(2016ZX05006001-003)
【分类号】：P618.13

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