狭长浅水湖盆分支河流体系演化过程和沉积模式——基于水槽沉积模拟实验【水槽沉积模拟实验专辑】
- 收稿日期:
2024-08-07
- 网络出版日期:
2025-03-04
摘要: 【目的】分支河流体系(DFS)广泛发育于现代和古代沉积地层中,是重要的油气储层。在低可容空间且物源供给充足的狭长浅水湖盆内可能发育多个互相影响的DFS,并演化出轴向河流。这种在狭长浅水湖盆内发育的多个DFS和轴向河流的发育过程、沉积特征、砂体展布规律以及各沉积单元之间的相互影响尚不明确。【方法】通过水槽模拟实验再现其沉积过程,使用高精度的3D扫描仪配合自研程序对沉积区进行三维可视化分析,明确DFS的阶段性演化特征。【结果】1)随着DFS规模扩大,DFS表面的水流逐渐聚集,初始流态为片流,随后演化为非限制性水流,最终为限制性水流;2)随着盆地可容纳空间变小,盆地内的轴向水流逐渐汇聚成轴向河流,轴向河流对两侧的DFS产生破坏作用并不断决口,最终在盆地内轴向河流下游形成大规模的河道沉积;3)狭长浅水湖盆发育多个DFS时,沉积砂体主要集中在物源附近的DFS处以及轴向河流下游,盆地发育时间越久,河流沉积规模越大。【结论】从盆地尺度描述了低可容空间且物源供给充足的狭长浅水湖盆内发育的多个DFS和轴向河流的发育过程及砂体展布规律,为油气勘探和分支河流体系研究提供理论支持。
Evolution and depositional model of distributive fluvial system in narrow and shallow lacustrine basin -- Insights from flume experimental simulation
- Received Date:
2024-08-07
- Available Online:
2025-03-04
Abstract: [Objective]Distributive fluvial system (DFS) are widely developed in modern and ancient sedimentary strata and are important hydrocarbon reservoirs. Multiple DFS interacting with each other and evolving axial rivers may be developed in narrow, shallow, narrow lacustrine basin with low accommodation. [Methods]Reproduced the deposition process through flume simulation experiments, and used a high-precision 3D scanner with a self-developed program to visual analysis the deposition area in three dimensions, to clarify the stage-by-stage evolution characteristics of the DFS. [Results and Discussions]1) with the expansion of the DFS scale, the water flow on the surface of the DFS gradually aggregates, and the initial flow pattern is sheet flow, then evolves into unrestricted flow, and finally restricted flow; 2) as the basin can accommodate less space, the axial water flow in the basin gradually aggregates into axial river, and the axial river has a destructive effect on the two sides of the DFS and constantly breaks, and finally forms a Large-scale fluvial deposition; 3) When multiple DFS are developed in a narrow shallow lacustrine basin, the sedimentary sands are mainly concentrated at the DFS near the source and downstream of the axial river, and the longer the basin development time, the larger the scale of fluvial deposition. [Conclusions]This paper describes the developmental processes and sand body spreading patterns of multiple DFS and axial rivers developed in a narrow, shallow lacustrine basin with low accommodation and sufficient supply of material sources at the basin scale, which provides theoretical support for oil and gas exploration and the study of distributive fluvial system.