奈曼凹陷北部义县组-九佛堂组沉积-地球化学环境恢复及其意义
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TE121.3+1;P595

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中国石油天然气股份有限公司科学研究与技术开发项目(2022KT0502); 辽河油田重大科技专项(2024KJZX-04, 2024QZJC-04)


Sedimentary geochemical environment restoration of Yixian Formation and Jiufotang Formation in the northern part of Naiman sag and its significance
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    摘要:

    为了确定奈曼凹陷北部下白垩统义县组-九佛堂组地球化学特征及古沉积环境,选取北部位于沉积中心附近的N10、NA-2井进行了岩相学分析,并对其中泥岩和蒸发岩样品进行了主量、微量元素、碳氧同位素和有机碳、热解、族组成等测试,系统分析了研究区的古氧化-还原条件、古盐度、古水深、古气候以及湖泊水体封闭性特征。研究结果表明,奈曼凹陷北部义县组沉积早期为火山岩相,沉积中期和末期主要为扇三角洲-湖相沉积体系,沉积末期局部地区为发育不同类型蒸发岩的滨浅湖相。Cu/Zn、Sr/Ba、Sr/Cu、Rb/Sr、Fe2O3/MnO、Ga、Sr等敏感元素或元素比值指示,义县组中期到末期气候由半湿润-半干旱变为干旱,水体环境也随之由偏氧化的半封闭-半开放到弱氧化-弱还原的完全闭塞,沉积地球化学环境由淡水-半咸水深湖变为咸化浅湖。九佛堂组则为半封闭条件下的氧化淡水深湖沉积,气候与义县组沉积中期相似。义县组沉积中期、末期和九佛堂组时期的沉积环境均适合生物繁殖,有利于泥质烃源岩的发育,而厚层蒸发岩溶蚀孔、晶间孔缝发育,能够成为良好的储集空间,有利于油气富集。

    Abstract:

    In order to determine the geochemical characteristics and paleosedimentary environment of the Lower Cretaceous Yixian Formation and Jiufotang Formation in the northern part of the Naiman sag, petrographic analysis was conducted on N10 and NA-2 wells located near the sedimentary center in the north. Samples of mudstone and evaporite were tested for major and trace elements, carbon and oxygen isotopes, organic carbon, pyrolysis, and group composition. The paleoredox conditions, paleosalinity, paleowater depth, paleoclimate, and lake water sealing characteristics of the study area were systematically analyzed. The study shows that they were volcanic facies in the early sedimentary period of Yixian Formation in the northern part of the Naiman sag, mainly fan delta-lacustrine depositional-lake facies sedimentary systems in the middle and late sedimentary period, and local shore-shallow lacustrine facies of different types of evaporites in the late sedimentary period. Sensitive elements or element ratios such as Cu/Zn, Sr/Ba, Sr/Cu, Rb/Sr, Fe2O3/MnO, Ga, Sr indicate that the climate of Yixian Formation changed from semi-humid-semi-arid to arid from the middle period to the end period, the water environment also changed from semi-closed-semi-open with partial oxidation to completely closed with weak oxidation-weak reduction, and the sedimentary geochemistry environment changed from freshwater-brackish deep lake to brackish shallow lake. The Jiufotang Formation is a semi-enclosed deep lake sedimentation of oxidized fresh water with a climate similar to that of the middle of the Yixian Formation. The sedimentary environment during the middle and late periods of the Yixian Formation and the Jiufotang Formation were suitable for biological reproduction, which were favorable for the development of argillaceous source rocks. And for the development of pores and intercrystalline pores of thick-layer evaporites, which can become good reservoir spaces, they are favorable for oil and gas enrichment.

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引用本文

刘海艳,刘兴周,蔡国刚,等, 2025. 奈曼凹陷北部义县组-九佛堂组沉积-地球化学环境恢复及其意义[J]. 岩石矿物学杂志, 44(2):325~344.
LIU Hai-yan, LIU Xing-zhou, CAI Guo-gang, et al, 2025. Sedimentary geochemical environment restoration of Yixian Formation and Jiufotang Formation in the northern part of Naiman sag and its significance[J]. Acta Petrologica et Mineralogica, 44(2): 325~344.

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  • 收稿日期:2023-12-16
  • 最后修改日期:2024-12-10
  • 在线发布日期: 2025-03-31
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