黑色页岩氧化还原条件与有机质富集机制——以昭通页岩气示范区A井五峰组-龙马溪组下段为例

发布时间：2018-03-29 20:51

  本文选题：氧化还原条件　切入点：有机质富集　出处：《石油与天然气地质》2017年05期

【摘要】：五峰组-龙马溪组下段为昭通示范区页岩气勘探开发的主要目的层段,基于A井样品有机碳、微量元素及稀土元素的系统测试,结合岩石学及测井资料,系统分析A井黑色页岩相关元素地球化学参数的变化特征,揭示黑色页岩形成的氧化还原条件,探讨有机质富集机制。研究结果表明:昭通页岩气示范区五峰组-龙马溪组下段Ⅰ亚段TOC含量最高,平均为3.13%,向上含量逐渐降低,且相关元素富集程度与TOC含量相关。微量元素及稀土元素等氧化还原参数指示:五峰组-龙马溪组下段,纵向上水体整体由厌氧还原环境向次氧化环境过渡,Ⅰ亚段为贫氧-厌氧环境,Ⅱ亚段为贫氧环境,Ⅲ亚段为贫氧-富氧环境。其中,Ⅰ-1小层、Ⅰ-3及Ⅰ-4小层水体还原性强于Ⅰ-2小层与I-5小层。在高古生产力背景下,五峰组与龙马溪组黑色页岩有机质富集的氧化还原环境形成机制存在差异。五峰组为水体滞留形成厌氧-贫氧环境使有机质有效保存,龙马溪组底部则主要由于海平面上升形成厌氧环境而使有机质有效保存富集。五峰组-龙马溪组下段I亚段有机质最为富集,为页岩气开发的最优层段。
[Abstract]:The lower member of Wufeng formation and Longmaxi formation is the main target section of shale gas exploration and development in Zhaotong demonstration area. Based on the systematic testing of organic carbon, trace elements and rare earth elements in well A, combined with petrology and logging data, The variation characteristics of geochemical parameters related to black shale in well A are systematically analyzed, and the redox conditions for the formation of black shale are revealed. The results show that the TOC content of the lower member of Wufeng formation and Longmaxi formation in Zhaotong shale gas demonstration area is the highest, with an average of 3.13, and the upward content decreases gradually. The redox parameters such as trace elements and rare earth elements indicated that the water body in the lower part of the Wufeng formation and Longmaxi formation was in a longitudinal transition from anaerobic reduction environment to secondary oxidation environment, and the enrichment degree of related elements was related to the content of TOC. The water bodies of submember 鈪，

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