石油与天然气地质 ›› 2023, Vol. 44 ›› Issue (2): 441-451.doi: 10.11743/ogg20230215

• 油气地质 • 上一篇    下一篇

断陷湖盆坡折带-古沟谷对沉积的控制作用

和子琛1(), 刘豪1(), 林鹤鸣2, 邱欣卫2, 汪旭东2, 剧永涛3, 阙晓明2   

  1. 1.中国地质大学(北京) 海洋学院,北京 100083
    2.中海石油(中国)有限公司 深圳分公司,广东 深圳 518000
    3.华北理工大学 矿业工程学院,河北 唐山 063210
  • 收稿日期:2022-08-01 修回日期:2022-11-16 出版日期:2023-03-17 发布日期:2023-03-17
  • 通讯作者: 刘豪 E-mail:3109596992@qq.com;lhcugb@163.com
  • 第一作者简介:和子琛(1996—),男,硕士研究生,矿产资源普查与勘探。 E-mail:3109596992@qq.com

Controlling effect of slope-break zone and paleovalley on sedimentation in rifted lake basins: A case study of the Paleogene Wenchang Formation in Haifeng 33 Subsag, Pearl River Mouth Basin

Zichen HE1(), Hao LIU1(), Heming LIN2, Xinwei QIU2, Xudong WANG2, Yongtao JU3, Xiaoming QUE2   

  1. 1.School of Ocean Sciences,China University of Geosciences,Beijing 100083,China
    2.Shenzhen Branch,CNOOC,Shenzhen,Guangdong 518000,China
    3.School of Mining Engineering,North China University of Science and Technology,Tangshan,Hebei 063210,China
  • Received:2022-08-01 Revised:2022-11-16 Online:2023-03-17 Published:2023-03-17
  • Contact: Hao LIU E-mail:3109596992@qq.com;lhcugb@163.com

摘要:

断陷湖盆的沉积充填受构造活动强度、海平面升降及物源供给通量的控制,而其内部砂体展布特征还受坡折带-古沟谷体系配置的调控,深入探索坡折带-古沟谷的配置关系对断陷湖盆油气勘探具有重要意义。珠江口盆地是南海重要的含油气盆地,盆地北部海丰33洼陷勘探程度较低,需要开展沉积体系发育控制因素分析,为储层的分布预测和油气勘探部署提供支撑。根据海丰33洼陷3D地震资料和测井资料,在区域构造解释基础上,深入剖析海丰33洼陷古近系文昌组发育的坡折带和古沟谷类型及其特征,阐明坡折带-古沟谷对沉积充填的控制作用。研究表明:①研究区文昌组发育断裂坡折、挠曲坡折和沉积坡折3种坡折带类型,自盆地边缘至沉积中心,坡折带具有多级分带的特征;②古沟谷类型以V型、U型、W型和单断槽型等4类为主,其中V型和U型沟谷数量较多且平面分布较为集中。坡折带控制了剥蚀区与物源区的边界,为沉积物输送提供了动力,控制了沉积物走向、搬运距离和沉积可容空间等。受坡折带组合的影响,研究区在不同阶段发育了不同的沉积体系类型。古沟谷作为沉积物搬运通道控制了沉积物的输送方向及卸载位置,且其大小控制了沉积体系的规模。因此,坡折带-古沟谷共同控制了沉积体系的类型、规模及其发育和演化。

关键词: 坡折带, 古沟谷, 古地貌, 沉积体系, 区域构造, 文昌组, 海丰33洼陷, 珠江口盆地

Abstract:

Rifted lake basins usually have their sedimentary filling controlled by the intensity of tectonic activities, sea level fluctuation and sediment flux. The distribution of sand bodies in these basins are also controlled by slope-break zones and paleovalley systems. It is of great significance to explore the configuration relationship between the slope break zones and paleovalley systems for oil and gas exploration in rifted lake basins. The Pearl River Mouth Basin is the most important petroliferous basin in the South China Sea. The less explored Haifeng 33 Subsag in the basin is selected to study the factors controlling the development of sedimentary systems so as to support the mapping of reservoirs and deployment of oil and gas exploration. Based on 3-D seismic data and logging data of the subsag as well as on the basis of regional structural interpretation, this paper analyzes the types and development characteristics of the slope-break zones and the paleovalleys of the Paleogene Wenchang Formation in the subsag, and clarifies the control of the slope-break zones and paleovalleys on sediment filling. The results show that there are three types of slope-break zones in the study area: fault slope-break zone, flexure slope-break zone and sedimentary slope-break zone. The paleovalleys are mainly V-shaped, U-shaped, W-shaped and single fault groove types, among which the V-shaped and U-shaped valleys are more in number and more concentrated in-plane distribution. The slope-break zones control the boundary of denudation and provenance, thus mobilizing the sediments in a certain direction for a certain distance within certain space. Different sedimentary systems are believed to be developed in different periods under the influence of these zones. Serving as transport channels, paleovalleys control the direction of sediment transport, location of sediment discharge as well as scale of depositional system. It is concluded that slope-break zones together with paleovalleys determine the types, scales, development and evolution of depositional systems.

Key words: slope-break belt, paleovalley, paleogeomorphology, sedimentary system, regional structure, Wenchang Formation, Haifeng 33 Subsag, Pearl River Mouth Basin

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