石油学报 ›› 2026, Vol. 47 ›› Issue (9): 1835-1849.DOI: 10.7623/syxb202609007

• 地质勘探 • 上一篇    

琼东南盆地中新统梅山组重力流-底流复合扇沉积模式与勘探意义

朱一杰1,2, 龚承林1,2, 胡林3, 尤丽3, 林璐3, 李一超1,2   

  1. 1. 油气资源与工程全国重点实验室,中国石油大学(北京) 北京 102249;
    2. 中国石油大学(北京)地球科学学院 北京 102249;
    3. 中海石油(中国)有限公司海南分公司 海南海口 570311
  • 收稿日期:2026-02-09 修回日期:2026-06-30 发布日期:2026-10-14
  • 通讯作者: 龚承林,男,1983年1月生,2014年获中国石油大学(北京)博士学位,现为中国石油大学(北京)教授、博士生导师,主要从事层序地层、源汇系统与深水沉积教学与研究工作。Email:chenglingong@cup.edu.cn
  • 作者简介:朱一杰,女,1998年6月生,2023年获中国石油大学(北京)硕士学位,现为中国石油大学(北京)博士研究生,主要从事深水沉积方面的研究。Email:yijiezhup2p@hotmail.com
  • 基金资助:
    新型油气勘探开发国家科技重大专项“南海油气成藏机制与勘探开发关键技术:02课题(深水中深层/超深层油气成藏机理与勘探开发关键技术)”(2025ZD1402702)资助。

Sedimentary model and exploration implications of hybrid turbidite-contourite fans in the Miocene Meishan Formation,Qiongdongnan Basin

Zhu Yijie1,2, Gong Chenglin1,2, Hu Lin3, You Li3, Lin Lu3, Li Yichao1,2   

  1. 1. State Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum (Beijing), Beijing 102249, China;
    2.College of Geosciences, China University of Petroleum, Beijing 102249, China;
    3.Hainan Branch, CNOOC China Limited, Hainan Haikou 570311, China
  • Received:2026-02-09 Revised:2026-06-30 Published:2026-10-14

摘要: 在琼东南盆地乐东—陵水凹陷中新统梅山组识别出一类新的深水海底扇沉积——重力流-底流复合扇。基于地震、钻井、测井和岩心等资料,结合岩心分析、粒度分析和岩石薄片分析等手段,系统分析了重力流-底流复合扇的沉积特征,建立了沉积模式,探讨了勘探意义。研究结果表明:①重力流-底流复合扇在形态上表现为扇体的长轴方向与区域等深线平行,在沉积样式上沿等深线方向持续稳定地叠置进积;在岩相上广泛发育层理构造,同时伴生与等深流相关的Zoophycos遗迹化石;其粒度累积概率曲线表现为2段或3段式结构,且部分样本数据在最粗颗粒粒径(C)与粒度中值(M)的关系(C—M图解)中落于牵引流沉积区;古生物种群显示扇体内有孔虫高度富集,并见Uvigerina spp.和Pullenia bulloides两类南海中层环流的指示种属。②重力流-底流复合扇是顺坡而下的重力流与沿坡流动的底流共同作用的结果,其在沉积构成上可划分为内扇、中扇和外扇3个亚相,其中,内扇亚相发育碎屑流沉积微相和高密度浊流沉积微相,中扇亚相发育强底流改造砂和弱底流改造砂微相,外扇亚相发育等深流沉积微相,不同亚相单元的物性差异主要受重力流与底流作用能量的相对变化所控制;内扇为重力流主导区,底流改造作用较弱,孔喉连通性差,发育中孔低渗的致密储层;中扇为重力流与底流交互作用区,底流对砂体的持续分选与淘洗作用显著改善了砂体的孔喉连通性,形成中孔中渗的优质储层;外扇为底流主导区,由等深流搬运而来的细粒沉积物在此堆积,表现为非储层。在中扇亚相的近物源一侧,扇体变窄处的强交互作用区,底流改造作用最强、储层物性最佳。重力流-底流复合扇沉积模式对识别、刻画深水陆缘重力流与底流交互作用形成的海底扇,以及预测优质底流改造砂具有指导意义。

关键词: 重力流-底流复合扇, 沉积模式, 中新统梅山组, 乐东—陵水凹陷, 琼东南盆地

Abstract: A new type of deep-water submarine fan deposit, termed a hybrid turbidite-contourite fan, was identified in the Miocene Meishan Formation of Ledong-Linshui sags, Qiongdongnan Basin. Based on seismic, drilling, logging, and core data, combined with core, grain-size, and thin-section analyses, the sedimentary characteristics of the hybrid turbidite-contourite fans were systematically investigated, a depositional model was established, and their exploration implications were discussed. The results indicate that the hybrid turbidite-contourite fans are characterized by fan elongation parallel to regional isobaths and persistent, stable progradational stacking along the contour direction. Their lithofacies are dominated by widespread bedding structures and commonly associated with contour-current-related Zoophycos trace fossils. Their grain-size probability cumulative curves exhibit two- or three-segment patterns, with some samples plotting within the traction-current depositional field on C-M diagrams. In addition, paleontological assemblages indicate a high abundance of foraminifera within the fans, including Uvigerina spp. and Pullenia bulloides, which are indicative of intermediate-water circulation in the South China Sea. The hybrid turbidite-contourite fans resulted from the combined action of downslope gravity flows and along-slope bottom currents and can be divided into inner-, middle-, and outer-fan subfacies. The inner-fan subfacies comprises debris-flow and high-density turbidity-flow microfacies, the middle-fan subfacies consists of strongly and weakly bottom-current-reworked sand microfacies, and the outer-fan subfacies is characterized by contourite microfacies. Differences in reservoir properties among these subfacies are mainly controlled by variations in the relative energy of gravity-flow and bottom-current processes. The inner fan is dominated by gravity flows, with weak bottom-current reworking and poor pore-throat connectivity, resulting in tight reservoirs with moderate porosity and low permeability. The middle-fan subfacies represents an interaction zone between gravity flows and bottom currents, where continuous sorting and winnowing by bottom currents significantly improve sand-body pore-throat connectivity, forming high-quality reservoirs with moderate porosity and permeability. The outer-fan subfacies is dominated by bottom currents, where fine-grained sediments transported by contour currents accumulate, forming non-reservoir intervals. Within the middle-fan subfacies, the strong interaction zone on the proximal side of the fan, where the fan narrows, exhibits the most intense bottom current reworking and the most favorable reservoir properties. The depositional model of hybrid turbidite-contourite fans provides guidance for identifying and characterizing submarine fans formed by the interaction of deep-water continental-margin gravity flows and bottom currents, as well as for predicting high-quality bottom-current-reworked sands.

Key words: hybrid turbidite-contourite fan, depositional model, Miocene Meishan Formation, Ledong-Linshui sags, Qiongdongnan Basin

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