石油与天然气地质 ›› 2023, Vol. 44 ›› Issue (6): 1595-1608.doi: 10.11743/ogg20230620

• 油气地质 • 上一篇    下一篇

砂质辫状河心滩沉积演化规律与沉积构型特征

雷涛1,2(), 任广磊2, 李晓慧2, 冯文杰3(), 孙华超2   

  1. 1.中国地质大学(武汉),湖北 武汉 430074
    2.中国石化 华北油气分公司 勘探开发研究院,河南 郑州 450006
    3.长江大学 地球科学学院,湖北 武汉 430100
  • 收稿日期:2023-05-08 修回日期:2023-10-20 出版日期:2023-12-01 发布日期:2023-12-20
  • 通讯作者: 冯文杰 E-mail:leitao.hbsj@sinopec.com;fwj1017@yangtzeu.edu.cn
  • 第一作者简介:雷涛(1983—),男,博士、高级工程师,沉积学、储层地质学。E-mail: leitao.hbsj@sinopec.com
  • 基金项目:
    国家自然科学基金青年项目(41802123);国家自然科学基金重点项目(42130813);中国石化科技项目(P20065)

Sedimentary evolution pattern and architectural characteristics of mid-channel bars in sandy braided rivers: Understanding based on sedimentary numerical simulation

Tao LEI1,2(), Guanglei REN2, Xiaohui LI2, Wenjie FENG3(), Huachao SUN2   

  1. 1.China University of Geosciences (Wuhan),Wuhan,Hubei 430074,China
    2.Exploration and Development Research Institute,North China Petroleum Bureau,SINOPEC,Zhengzhou,Henan 450006,China
    3.School of Geosciences,Yangtze University,Wuhan,Hubei 430100,China
  • Received:2023-05-08 Revised:2023-10-20 Online:2023-12-01 Published:2023-12-20
  • Contact: Wenjie FENG E-mail:leitao.hbsj@sinopec.com;fwj1017@yangtzeu.edu.cn

摘要:

砂质辫状河心滩砂体规模大、连通性强、物性较好,是一类重要的油气储层。受到复杂多变的水动力条件影响,心滩呈现出类型多样、内部构型特征复杂等特征,制约了油气资源高效开发。为探索砂质辫状河心滩沉积演化规律及其控制的沉积构型特征,采用基于水动力场实时求解的沉积数值模拟方法,开展砂质辫状河沉积演化动态模拟和过程解析,结果表明:①砂质辫状河心滩的演化过程包括5个阶段,表现为菱形坝、舌形坝、单元坝、复合坝及改造复合坝的顺次形成和连续转换,各类心滩平面形态、剖面结构样式及定量规模存在显著差异;②水流与心滩的交互作用是主导砂质辫状河沉积演化的主控机理,即水流聚散特征与分布样式的持续变化导致心滩形成、增生、迁移、形变并遭受频繁、复杂的叠切,而心滩的演化又进一步导致水流聚散特征与分布样式的变化;③心滩内部发育前积、侧积及加积3类增生体,从菱形坝形成到改造复合坝发育,心滩内部增生体类型由前积主导转变为前积与侧积共生并最终变为前积、侧积及加积复杂复合,心滩长度、宽度由快速增加转变为缓慢增加并最终维持稳定,沉积记录中终止于不同演化阶段的辫状河心滩储层平面分布样式、内部构型特征及定量规模存在较大差异。

关键词: 定量规模, 沉积数值模拟, 沉积演化, 沉积构型, 心滩, 砂质辫状河

Abstract:

Mid-channel bars in sandy braided rivers, boasting a large scale, high connectivity, and favorable physical properties, serve as a significant type of hydrocarbon reservoirs. Complex and variable hydrodynamic conditions endow mid-channel bars with multiple types and complex internal architectures, which constrain efficient oil and gas exploitation. This study aims to explore the sedimentary evolution pattern and architectural characteristics of mid-channel bars in sandy braided rivers, with a specific focus on the influence of the sedimentary process. To this end, we conduct the dynamic simulation and process analysis of the sedimentary evolution of sandy braided rivers using a sedimentary numerical simulation method based on the real-time solution in hydrodynamic fields. The results are as follows: (1) Mid-channel bars in sandy braided rivers evolve in five stages, namely the sequential formation and continuous conversion of lozenge-shaped bars, tongue-shaped bars, unit bars, composite bars, and reworked composite bars. These bars differ significantly in planar morphology, cross-sectional structure, and scale; (2) Interactions between water currents and mid-channel bars act as the predominant mechanism governing the sedimentary evolution of sandy braided rivers. Specifically, the constant changes in the convergence and divergence characteristics and distribution styles of water currents facilitate the formation, accretion, migration, and deformation of the mid-channel bars, which are under frequent and complex superimposition and cutting. In turn, the evolutionary dynamics of the mid-channel bars further induces the above-mentioned changes in water currents; (3) Three types of accretion stemming from progradation, lateral accretion, and aggradation occur within the mid-channel bars. In the process from the formation of lozenge-shaped bars to the emergence of reworked composite bars, the accretion within mid-channel bars evolves from an initial dominance of progradation to the coexistence of progradation and lateral accretion, culminating in a combination of all three accretion types. During the transitional phase, the length and width of the mid-channel bars experience a rapid increase, followed by a slow increase, and finally stabilize. As revealed by sedimentary records, reservoirs of the mid-channel bar microfacies terminating at different evolutionary stages differ significantly in planar distribution pattern, internal architectural characteristics, and scale.

Key words: quantitative aspect, sedimentary numerical simulation, sedimentary evolution, sedimentary architecture, mid-channel bar, sandy braided river

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