石油与天然气地质 ›› 2025, Vol. 46 ›› Issue (5): 1504-1521.doi: 10.11743/ogg20250508

• 油气地质 • 上一篇    

深水重力流沉积类型及含油性对比——以鄂尔多斯盆地富县地区三叠系延长组长7—长9油层组为例

王琳茜1,2(), 赵靖舟1,2(), 高振东3, 魏繁荣3, 周世琪1,2, 孟选刚3, 闫新智3, 徐宁3   

  1. 1.西安石油大学 地球科学与工程学院,陕西 西安 710065
    2.西安石油大学 陕西省油气成藏地质学重点实验室,陕西 西安 710065
    3.延长油田股份有限公司,陕西 延安 716000
  • 收稿日期:2025-06-17 修回日期:2025-08-14 出版日期:2025-10-30 发布日期:2025-10-29
  • 通讯作者: 赵靖舟 E-mail:1474153226@qq.com;jzzhao@xsyu.edu.cn
  • 第一作者简介:王琳茜(2002—),女,硕士研究生,地质资源与地质工程。E-mail: 1474153226@qq.com
  • 基金项目:
    国家科技重大专项(2016ZX05050)

Types of deep-water gravity-flow deposits and comparison of their oil-bearing properties: A case study of the 7th-9th oil groups in the Triassic Yanchang Formation, Fuxian area, Ordos Basin

Linxi WANG1,2(), Jingzhou ZHAO1,2(), Zhendong GAO3, Fanrong WEI3, Shiqi ZHOU1,2, Xuangang MENG3, Xinzhi YAN3, Ning XU3   

  1. 1.School of Earth Sciences and Engineering,Xi’an Shiyou University,Xi’an,Shaanxi 710065,China
    2.Shaanxi Key Laboratory of Petroleum Accumulation Geology,Xi’an Shiyou University,Xi’an,Shaanxi 710065,China
    3.Yanchang Oil Field Co. ,Ltd. ,Yan’an,Shaanxi 716000,China
  • Received:2025-06-17 Revised:2025-08-14 Online:2025-10-30 Published:2025-10-29
  • Contact: Jingzhou ZHAO E-mail:1474153226@qq.com;jzzhao@xsyu.edu.cn

摘要:

三叠系延长组7—9油层组(长7—长9油层组)是鄂尔多斯盆地富县地区石油资源潜力较大的层系,以往研究多认为该套地层的砂岩主要为三角洲沉积,近年研究虽然在长7油层组发现了重力流沉积,但长7—长9油层组是否都有重力流沉积及其分布范围如何仍不清楚。综合岩心观察、粒度分析和薄片观察等手段,判识重力流沉积的主要类型及其分布,并对不同类型重力流沉积的储层特征与含油性进行对比分析,结果显示:①富县地区长7—长9油层组普遍发育重力流沉积,包括砂质碎屑流沉积、浊流沉积和滑动-滑塌沉积3种类型。其中砂质碎屑流沉积砂体厚度较大,发育块状层理,可见泥岩撕裂屑,概率累积曲线主要为偏粗的一段式、短尾两段式和悬浮组分含量较高的两段式;浊流沉积较薄,岩心中可观察到不完整鲍玛序列,概率累积曲线主要为偏细的一段式;滑动-滑塌沉积以揉皱变形、包卷层理和阶梯状断层为特征。②砂质碎屑流沉积普遍优于浊流沉积,具有储层品质佳、含油性好和试油产量高等特征。③富县地区长7—长9油层组普遍发育重力流沉积,砂质碎屑流沉积最为发育,其储层物性和含油性也最好,建议作为今后该地区致密油勘探开发的主要目标。

关键词: 含油性, 砂质碎屑流沉积, 浊流沉积, 滑动-滑塌沉积, 重力流沉积, 富县地区, 鄂尔多斯盆地

Abstract:

In the Fuxian area of the Ordos Basin, the 7th‒9th oil groups in the Triassic Yanchang Formation (also referred to as the Chang 7‒9 oil groups) hold great petroleum resource potential. Previous studies mostly hold that sandstones in these oil groups are dominated by deltaic deposits. Although gravity-flow deposits have been discovered in the Chang 7 oil group in recent years, some issues remain unclear, including their existence and distribution range across the Chang 7‒9 oil groups. Using core observations, grain size analysis, and thin section observations, we identify the primary types of gravity-flow deposits and their distributions, together with the comparison of reservoir characteristics and oil-bearing properties within. The results indicate that gravity-flow deposits are widely distributed across the Chang 7‒9 oil groups in the Fuxian area, including sandy debris-flow deposits, turbidite-flow deposits, and slide-slump deposits. The sandy debris-flow deposits, among others, feature great thicknesses and massive beddings, with rip-up clasts visible. Their grain-size cumulative probability curves exhibit three primary patterns: a coarse-skewed single-segment pattern, a short-tailed two-segment pattern, and a two-segment pattern with high suspended component content. In contrast, the turbidite-flow deposits are thin, with incomplete Bouma sequences observable in cores. Their grain-size cumulative probability curves primarily show a fine-skewed single-segment pattern. In contrast, the slide-slump deposits are characterized by wrinkling deformation, convolute beddings, and stepped faults. The comparison reveals that the sandy debris-flow deposits are generally superior to the turbidite-flow deposits, exhibiting high reservoir quality, favorable oil-bearing properties, and high daily oil production from well tests. Among the widespread gravity-flow deposits in the Chang 7‒9 oil groups in the Fuxian area, the sandy debris-flow deposits show the most extensive distribution, as well as the most favorable reservoir physical properties and oil-bearing properties. Therefore, they should be prioritized as significant targets for future exploration and development of tight oil in the Fuxian area.

Key words: oil-bearing property, sandy debris-flow deposits, turbidite-flow deposits, slide-slump deposits, gravity-flow deposits, Fuxian area, Ordos Basin

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