石油与天然气地质 ›› 2023, Vol. 44 ›› Issue (4): 869-886.doi: 10.11743/ogg20230406

• 油气地质 • 上一篇    下一篇

松辽盆地古龙凹陷白垩系青山口组页岩层序等时格架下的有机质分布规律

张天舒1(), 朱如凯1(), 蔡毅1, 王华建1, 吕丹1, 周海燕1, 付秀丽2, 刘畅1, 崔坤宁2, 张素荣1, 王浡3, 吴松涛1, 张婧雅1, 姜晓华1, 冯有良1, 刘合1   

  1. 1.中国石油 勘探开发研究院,北京 100083
    2.中国石油 大庆油田公司,黑龙江 大庆 163712
    3.北京大学 能源研究院,北京100871
  • 收稿日期:2023-02-22 修回日期:2023-05-20 出版日期:2023-08-01 发布日期:2023-08-09
  • 通讯作者: 朱如凯 E-mail:zhangtianshu@petrochina.com.cn;zrk@petrochina.com.cn
  • 第一作者简介:张天舒(1982—),女,博士、高级工程师,层序地层与沉积地质。E-mail:zhangtianshu@petrochina.com.cn
  • 基金项目:
    黑龙江省揭榜挂帅项目(RIPED-2022-JS-1740)

Distribution of organic matter in the Qingshankou Formation Shale, Gulong Sag, Songliao Basin observed within an isochronous sequence stratigraphic framework

Tianshu ZHANG1(), Rukai ZHU1(), Yi CAI1, Huajian WANG1, Dan LYU1, Haiyan ZHOU1, Xiuli FU2, Chang LIU1, Kunning CUI2, Surong ZHANG1, Bo WANG3, Songtao WU1, Jingya ZHANG1, Xiaohua JIANG1, Youliang FENG1, He LIU1   

  1. 1.Research Institute of Petroleum Exploration & Development,PetroChina,Beijing 100083,China
    2.Daqing Oilfield Company,PetroChina,Daqing,Heilongjiang 163002,China
    3.Institute of Energy,Peking University,Beijing 100871,China
  • Received:2023-02-22 Revised:2023-05-20 Online:2023-08-01 Published:2023-08-09
  • Contact: Rukai ZHU E-mail:zhangtianshu@petrochina.com.cn;zrk@petrochina.com.cn

摘要:

松辽盆地古龙凹陷白垩系青山口组陆相纯页岩型页岩油获得高产突破,但古龙页岩有机质分布的非均质性强,主控因素不清,制约有利区和甜点段预测。通过精细分析岩心、露头、薄片、地震、测井、地球化学和古生物等数据,针对湖相深水页岩特点,基于“层序等级”与“湖侵-湖退(T-R)旋回”理论,结合天文旋回研究进展,建立了深湖区高频层序等时格架。通过类比现代湖泊,建立了古湖泊沉积环境判识指标,分析了古生产力、氧化还原环境及沉积速率的耦合关系,探讨了高频层序格架下有机质富集非均质性的成因。研究认为:①古龙凹陷青山口组可划分为4个三级层序,其中,层序1和层序2识别出2个T-R旋回,由13个准层序组(52个准层序)构成;准层序和准层序组的沉积时长分别为约40 kyr和170 kyr。②层序格架下页岩发育3种岩相、4种纹层、5种组合类型、11种纹层组合模式和3种沉积微相;T-R旋回控制了沉积微相、岩相和纹层组合的纵向分布,其中,深湖相静水沉积和泥流沉积的黏土质页岩为有利岩相。③T-R旋回控制了有机质分布,湖泛面附近是有利部位;有利区/段为古龙凹陷的准层序组2以及三肇凹陷的准层序组1—4。该研究成果能够为页岩油有利区和甜点段预测提供沉积学依据。

关键词: 有机质富集, 沉积环境, 层序地层, 古龙页岩, 松辽盆地

Abstract:

The Qingshankou Formation shale, Gulong Sag, Songliao Basin, has been gushing out oil in a rate stunning the Chinese oil industry. However, further prediction of sweet spots in the formation remains a challenge due to the highly uneven distribution of organic matter and confusion in the understanding of controlling factors. This study adopted the concepts of “hierarchy in sequence stratigraphy” and “transgressive-regressive (T-R) sequences”, with updated astronomical cycle research results to determine the accurate duration of sequences and re-establish an isochronous sequence stratigraphic framework specifically for lacustrine deep-water shale based on core, outcrop, and thin section observation, as well as seismic profile, well-logging, geochemical, and paleontological data analyses from a microcosmic to macroscopic scale. Subsequently, using modern lakes sedimentation as an analogy made it possible to propose qualitative and quantitative indexes for identifying paleo-water environment, and probe into the origin of the heterogeneity of organic matter enrichment under the sequence stratigraphic framework on the basis of the coupling relation among paleoproductivity, redox conditions, and sedimentation rate. The main conclusions are as follows: 1) There are four third-order sequences in Qingshankou Formation Shale, Gulong Sag, Songliao Basin. Among them, SQ1 and SQ2 consist of two T-R sequences of 13 parasequence sets (made up of 52 parasequences). The durations of parasequence and parasequence set are approximately 40 kyr and 170 kyr, respectively. 2) Three types of lithofacies, four types of laminae, five laminae combinations, eleven laminae combination patterns, and three sedimentary microfacies have been recognized under the sequence stratigraphic framework. T-R cycles control the vertical distribution of laminae combination, lithofacies and sedimentary microfacies. The argillaceous shales deposited in deep-lake stagnant water and mud flow are prospective lithofacies. 3) T-R cycles control the enrichment of organic matter and different orders of flooding surfaces are the favorable locations for organic matter enrichment. Parasequence set 2 in Gulong Sag and parasequence sets 1 to 4 in Sanzhao Sag have been evaluated to be the most promising exploration targets. This study aims to provide sedimentological evidence for shale oil target area and “sweet spots” prediction.

Key words: organic matter enrichment, sedimentary environment, sequence stratigraphy, Gulong Shale, Songliao Basin

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