摘要
河控三角洲是一类对油气勘探有重要意义的沉积体系,采用三维水动力数值模拟的方法正演模拟了河控三角洲的形成过程并精确分析了其分支河道的演化规律。利用Delft3D建立了河控三角洲的三维水动力数值模型,根据现代河流与三角洲的水动力特征,设计了其沉积过程的模拟条件。计算域长20.5km,宽10km,在地貌演化系数(Mor-Factor)为60倍的情况下模拟时长4个月,约120d。通过对河控三角洲的模拟分析了河口砂坝的形成与冲蚀,分支河道的延伸、迁移和分叉,通过垂向剖面观察到分支河道的多期次充填。用定量的手段结合分支河道演化特征表明河控三角洲在没有波浪和潮汐作用的静水体中分支河道极其发育,只要空间足够大即可发育无数条的分支河道。研究表明在河控三角洲发育的后期分支河道的交叉切割与改造可形成连片的沉积体,这与在波浪和潮汐改造作用下所形成的连片朵状三角洲在成因机理上不同。该研究结果表明利用水动力数值模拟的方法可以较好地揭示河控三角洲分支河道的演化过程。
The fluvial-dominated delta is one of the extremely important deposition systems in oil and gas exploration. In this paper, the three-dimensional numerical simulation of hydrodynamics has been applied in the precise analysis of the formation of fluvial-dominated deltas and the evolution of their distributary channels. The model has been created by Delft3D, and the conditions of the numerical model have been set according to the hydrodynamic characteristics of modern rivers and deltas. The calculation field was 20.5 km in length by 10 km in width. With the Mor-Factor set to 60, the simulation time was about 120 days. The formation and the avulsion of the mouth bar, as well as the extension, migration and bifurcation of distributary channels, have been observed and studied through analysis of the simulation results. The ver- tical cross-section shows that the distributary channel was filled multiple times. According to distributary channel evolution characteristics combined with quantitative methods, the terminal distributary channels can be well developed under ideal conditions. Due to the cross-cutting and reform of distributary channels, sediments were spread widely and continuously. The results show that the numerical model works well in explaining the process of evolution in fluvial-dominated delta distributary channels. This study not only en- ables the quantitative understanding of the dynamic processes of terminal distributary channels in fluvial- dominated delta systems, but also provides a reference model for numerical simulation of hydrodynamics in sedimentology study.
出处
《地质科技情报》
CAS
CSCD
北大核心
2016年第1期44-52,共9页
Geological Science and Technology Information
基金
国家自然科学基金项目(41072087
41172106)
国家科技重大专项(2011ZX05010-002-004)
关键词
水动力数值模拟
河控三角洲
分支河道
Delft3D
定量沉积学
numerical simulation of hydrodynamics
fluvial-dominated delta
distributary channel
Delft3D
quantitative sedimentology
