古地理学报 ›› 2025, Vol. 27 ›› Issue (3): 611-624. doi: 10.7605/gdlxb.2025.022

• 岩相古地理学及沉积学 • 上一篇    下一篇

高精度层序格架下湖底扇沉积特征及演化:以鄂尔多斯盆地庆北长7段为例*

叶定蓬1(), 何云龙1(), 侯秀林2, 周波2, 王磊飞3, 张先平4, 李国顺1, 刘佳钰1, 向常龙1, 张涵4, 吕德杰5   

  1. 1 海洋地质资源湖北省重点实验室(中国地质大学(武汉)),湖北武汉 430074
    2 中国石油勘探开发研究院,北京 100083
    3 长庆油田陇东油气开发分公司,甘肃庆阳 745000
    4 中国地质大学(武汉)资源学院,湖北武汉 430074
    5 内蒙古自治区自然资源厅综合保障中心,内蒙古呼和浩特 010041
  • 收稿日期:2024-01-31 修回日期:2024-07-16 出版日期:2025-06-01 发布日期:2025-05-29
  • 通讯作者: 何云龙,男,1983年生,博士后,副教授,长期从事沉积物重力流沉积及其资源环境效应研究。E-mail: ylhe@cug.edu.cn。
  • 作者简介:

    叶定蓬,男,1999年生,硕士研究生,研究方向为含油气盆地沉积体系分析。E-mail:

  • 基金资助:
    *国家自然科学基金项目(41502102); 国家自然科学基金项目(42072137)

Sedimentary characteristics and evolution of sublacustrine fan in high-resolution sequence stratigraphic framework: a case study of the Chang 7 Member in Qingbei area,Ordos Basin,China

YE Dingpeng1(), HE Yunlong1(), HOU Xiulin2, ZHOU Bo2, WANG Leifei3, ZHANG Xianping4, LI Guoshun1, LIU Jiayu1, XIANG Changlong1, ZHANG Han4, LÜ Dejie5   

  1. 1 Hubei Key Laboratory of Marine Geological Resources,China University of Geosciences(Wuhan),Wuhan 430074,China
    2 PetroChina Research Institute of Petroleum Exploration and Development,Beijing 100083,China
    3 Longdong Oil and Gas Development Company of Changqing Oil Field,Gansu Qingyang 745000,China
    4 Faculty of Earth Resources,China University of Geosciences(Wuhan),Wuhan 430074,China
    5 Comprehensive Security Center of Inner Mongolia Autonomous Region Department of Natural Resources,Hohhot 010041,China
  • Received:2024-01-31 Revised:2024-07-16 Online:2025-06-01 Published:2025-05-29
  • Contact: HE Yunlong,born in 1983,postdoctor,associate professor,has long been engaged in research on sediment gravity flow deposition and its resource and environmental effects. E-mail: ylhe@cug.edu.cn.
  • About author:

    YE Dingpeng,born in 1999,is a master degree candidate. His research direction is sedimentary system analysis of petroleum basin. E-mail: .

  • Supported by:
    National Natural Science Foundation of China(41502102); National Natural Science Foundation of China(42072137)

摘要:

湖底扇是近年来鄂尔多斯盆地油气勘探的热点目标之一,具有重要的油气勘探价值。湖底扇发育受到多种因素的影响,不同地质背景下的湖底扇沉积演化特征差异性明显。本次研究以鄂尔多斯盆地延长组7段湖底扇为研究对象,综合利用岩心、测井及地震等资料,在高精度层序格架内对庆北地区长71层序单元的湖底扇展开沉积演化分析。研究表明,依据四级层序长71内部岩性突变面,长71层序单元可划分出5个五级层序单元,重点五级层序单元71-5及71-4可进一步划分出10个六级层序单元。本次研究识别出重力流水道、水道天然堤复合体、天然堤、朵体和朵体边缘等不同的湖底扇沉积单元。研究表明,研究区湖底扇主要由辫状河三角洲前缘供源,在湖平面持续下降及温暖潮湿的气候背景下,陆源碎屑输入量高,辫状河三角洲前缘物源供给增强,湖盆可容纳空间下降,湖底扇向东北方向进积,朵体范围变大,具有横向连片、纵向叠置的沉积特征。

关键词: 长7段, 重力流, 湖底扇, 沉积特征, 鄂尔多斯盆地

Abstract:

In recent years,sublacustrine fans have emerged as a prime focus for oil and gas exploration in the Ordos Basin due to their immense potential. However,their development is influenced by multiple factors,leading to distinct sedimentary evolution patterns under varying geological settings. This study focuses on the sublacustrine fan in the Chang 7 Member of Yanchang Formation in the Ordos Basin. By integrating core,well logs,and seismic data,a detailed analysis of the sedimentary evolution of the Chang 71 sequence unit's sublacustrine fan in the Qingbei area was conducted within a high-resolution sequence framework. The results show that the Chang 71 sequence unit can be systematically divided into five distinct fifth-order sequence units,based on lithological discontinuity surfaces within the fourth-order sequence. Notably,the crucial fifth-order sequence units,71-5 and 71-4,can be further subdivided into 10 sixth-order sequences. The present study successfully distinguished various sedimentary units within the sublacustrine fan,including gravity flow channel,channel-levee complex,levee,lobe,and lobe edge. Given the sedimentary background,the sublacustrine fan in the study area is interpreted to be mainly sourced from the braided river delta front. The results indicate that during periods of lake-level fall under warm and humid climatic conditions,increased terrigenous clastic input enhanced sediment suppy from the braided river delta front,and the accommodation space of the lake basin decreased,facilitating northeastward progradation of the sublacustrine fan,with expanding depositional lobes showing distinct lateral migration patterns.

Key words: Chang 7 Member, gravity flow, sublacustrine fan, sedimentary characteristics, Ordos Basin

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