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坡度对浊流流动及沉积影响的三维数值模拟

Three-dimensional Numerical Simulation of the Influence of Slope on Turbidity Flow and Deposition

  • 摘要: 采用自行开发的首款具有智能网格生成功能的Simusoft软件生成水下直梯形及弯曲梯形渠道三维模型网格,模拟分析坡度对渠道浊流流速、浊流密度、沉积厚度及沉积物粒径分布的影响。结果表明:随坡度增加直梯形和弯曲梯形渠道内的浊流流速均呈非线性变化,垂向断面流速极大值更趋于底床;直梯形渠道内坡折处浊流密度最大,随坡度增大浊流头部密度衰减较快;弯曲梯形渠道内随坡度增大浊流密度增加,且浊流的外溢逐渐增强;多次浊流事件在低坡折渠道中的沉积量由上游往下游逐渐减少,高坡折渠道则为上游侵蚀增强而坡折后的沉积增加。本文研究对根据观测浊积岩特征,推断浊积岩形成环境,进而确定相关的浊流机制以及可能的油藏规模等有一定的参考。

     

    Abstract: The first self-developed Simusoft software with intelligent grid generation was used to generate three-dimensional model grids of underwater straight trapezoid and curved trapezoid channels. The influences of slope on turbidity current velocity, turbidity current density, deposition thickness and sediment particle size distribution in straight and curved trapezoid channels were simulated and analyzed. The results show that with the increase of slope, the flow velocity of both straight and curved channels is non-linear , and the maximum flow velocity of vertical section tends towards the bottom bed. The turbidity density in the straight channel reaches the maximum at the slope break, and the turbidity head density decreases faster with the increase of the slope. The turbidity density in the curved channel also increases with the increase of the slope, and the turbidity overflow is gradually enhanced. The sediment amount of multiple turbidity-current events in low slope break channels gradually reduce from the upper stream to the lower stream. While in the high slope break channels, the upper stream erosion increases and the deposition increases after the slope break. This study has a certain reference function for inferring the formation environment of turbidite based on the observation of turbidite characteristics, and then determining the relevant turbidity current mechanism and possible reservoir size.

     

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