石油与天然气地质 ›› 2022, Vol. 43 ›› Issue (4): 957-969.doi: 10.11743/ogg20220417

• 方法技术 • 上一篇    下一篇

湖相泥页岩地层米氏旋回测井识别及环境响应特征

彭军1(), 于乐丹1(), 许天宇1, 韩浩东2, 杨一茗1, 曾垚1, 王瑜斌1   

  1. 1.西南石油大学 地球科学与技术学院,四川 成都 610500
    2.中国地质调查局 成都地质调查中心,四川 成都 610081
  • 收稿日期:2022-01-06 修回日期:2022-04-29 出版日期:2022-07-14 发布日期:2022-07-14
  • 通讯作者: 于乐丹 E-mail:pengjun@swpu.edu.cn;yldxsyhxs@126.com
  • 第一作者简介:彭军(1968—),男,教授、博士生导师,沉积学、储层地质学及层序地层学。E?mail: pengjun@swpu.edu.cn
  • 基金项目:
    国家自然科学基金面上项目(41872166)

Logging identification of Milankovitch cycle and environmental response characteristics of lacustrine shale—A case study on Es4scs in Well Fanye 1, Dongying Sag, Jiyang Depression, Bohai Bay Basin

Jun Peng1(), Ledan Yu1(), Tianyu Xu1, Haodong Han2, Yiming Yang1, Yao Zeng1, Yubin Wang1   

  1. 1.School of Geoscience and Technology,Southwest Petroleum University,Chengdu,Sichuan 610500,China
    2.Chengdu Institute of Geology and Mineral Resources,China Geological Survey,Chengdu,Sichuan 610081,China
  • Received:2022-01-06 Revised:2022-04-29 Online:2022-07-14 Published:2022-07-14
  • Contact: Ledan Yu E-mail:pengjun@swpu.edu.cn;yldxsyhxs@126.com

摘要:

旋回地层学因具备高时间精度特性而被广泛应用于沉积地层的高精度地质定年和高分辨率地层划分与对比等研究领域。细粒沉积地层的旋回划分研究由于难度大,一直是层序地层学研究的重点和难点。以渤海湾盆地济阳坳陷东营凹陷樊页1井古近系沙河街组四段上亚段纯上次亚段(Es4scs)湖相泥页岩为研究对象,选取测井数据和地球化学分析数据作为旋回分析的替代指标,采用频谱分析、小波变换、功率谱估计和滤波分析相结合的手段,对研究层段记录的米兰科维奇旋回(米氏旋回)进行识别;并结合地球化学指标验证测井数据识别旋回的可行性;在米氏旋回识别的基础上建立了“浮动”天文年代标尺,计算了沉积速率;同时,首次在研究区探索性地运用沉积有机质丰度和表征古氧化-还原性的指标探讨了轨道周期的响应特征。研究结果表明:① 湖相泥页岩沉积旋回明显受米氏旋回控制,包括405.00 kyr偏心率长周期(E1),124.22 kyr偏心率短周期(E2),39.76 kyr斜率周期(O2)以及22.00 kyr岁差周期(P1);② 研究层段共识别出6个E1,22个E2,65个O2和110个P1,依据“浮动”天文年代标尺计算出沉积时间为2.73 Myr,平均沉积速率为0.069 m/kyr;③ 湖相细粒沉积地层有机质丰度及古氧化-还原性变化受天文周期控制;④ 当偏心率振幅幅度较大且处于最大值时期,地球整体处于间冰期,气候暖湿,易于形成富有机质沉积地层,是页岩油勘探的最有利层段。研究提出的思路和方法为同类型细粒沉积地层的旋回划分与对比、“浮动”天文年代标尺的建立、沉积速率的计算以及有机质富集规律的研究提供了参考,研究成果直接应用于东营凹陷沙河街组细粒沉积地层的非常规油气勘探开发。

关键词: 米兰科维奇旋回, 天文年代标尺, 沉积速率, 轨道周期, 环境响应, 页岩油勘探, 沙河街组, 东营凹陷

Abstract:

Cyclostratigraphy is widely used in fields such as high-precision geological dating of sedimentary strata and high-resolution stratigraphic division and comparison due to its high timing accuracy. The study on cycle division of fine-grained sedimentary strata has been the focus in sequence stratigraphy, though the difficulty. The lacustrine shale from the upper interval of the upper sub-member of the 4th member of the Paleogene Shahejie Formation (Es4scs) in Well Fanye 1, Dongying Sag, Jiyang Depression, Bohai Bay Basin is taken to identify the Milankovitch cycles recorded in the interval. Both logging and geochemical data are selected as alternative indicators for cycle analysis. A combination of spectrum analysis, wavelet transform, power spectrum estimation, and filter analysis is applied to identify the Milankovitch cycles, and geochemical indicators are used to verify the feasibility of logging data-based cycle identification. Subsequently, a “floating” astronomical time scale is established to calculate the sedimentation rate. At the same time, the abundance of organic matter in sediments and paleo-redox proxies are in exploratory application to discuss the response characteristics of the orbital periodicities. The research results are shown as follows. First, it is obvious that the sedimentary cycles of lacustrine shale are significantly controlled by Milankovitch cycles, including 405.00-kyr long-eccentricity cycle (E1), 124.22-kyr short-eccentricity cycle (E2), 39.76-kyr obliquity cycle (O2) and 22.00-kyr precession cycle (P1). Second, a total of 6 E1, 22 E2, 65 O2, and 110 P1 are identified in the studied interval. According to the “floating” astronomical time scale, the duration of deposition may be 2.73 Myr with an average sedimentation rate of 0.069 m/kyr. Third, the abundance of organic matter and variation of the paleo-redox conditions in the fine-grained lacustrine sedimentary strata are controlled by astronomical cycles. Fourth, when the amplitude of eccentricity is large and at its maximum, the earth as a whole is in the interglacial period, warm and humid, prone to generate anoxic organic-rich sedimentary strata, which are the most favorable targets for shale oil exploration. In all, the ideas and methods proposed in the study are of referential value to the division and comparison of cycles of the same type of fine-grained sedimentary strata, the establishment of “floating” astronomical time scales, the calculation of sedimentation rates, and the study of organic matter enrichment rules. In addition, the research results have been directly applied to the unconventional oil and gas exploration and development in the fine-grained sedimentary strata of Shahejie Formation in the Dongying Sag.

Key words: Milankovitch cycle, astronomical time scale, sedimentation rate, orbital periodicity, environmental response, shale oil exploration, Shahejie Formation, Dongying Sag

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