海底大弯曲渠道中浊流流动和沉积特征的研究

发布时间：2018-01-05 01:33

本文关键词：海底大弯曲渠道中浊流流动和沉积特征的研究　出处：《安徽工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：对浊流在海底弯曲渠道中的流动及沉积的研究因其和海洋油气资源的密切关系一直为研究热点之一。目前海底实测和实验室研究都有很多困难和不足之处,随着计算机技术的飞速发展,三维数值模拟成为研究浊流越来越重要的手段。本研究选用基于雷诺平均的纳维尔—斯托克斯方程和经过浮力项修正的k-ε湍流模型及正交化的结构网格对大弯曲度(1.32、1.56和1.82)、流向坡度为0.069°的梯形渠道内及其漫滩的浊流的流动及其沉积或侵蚀进行了三维数值模拟,得到大弯曲度梯形渠道中浊流流动、二次流及沉积的如下特征:(1)周围流体的夹带作用强,弯道顶点断面处的密度等值面的倾斜度随着弯曲度的增加而增加;(2)上游弯道顶点外岸的剥离流又进入下游渠道内,使得下游的流动和沉积更加复杂;(3)渠道底部的外岸处存在比低弯曲度弱的类似河流的二次流;(4)浊流多次流动后弯道内岸处有一定侵蚀,渠道底内沉积呈现由内岸向外岸的波状倾斜;(5)从紧贴弯曲渠道边缘的纵向剖面上观察的沉积比低弯曲度的更加波状起伏,波谷处恰好对应弯道顶点外侧;(6)从切过渠道内部及堤坝的纵向剖面上观察的沉积除呈现较薄的边坡拱形沉积间隔以较厚的渠底沉积外,比低弯曲度渠道更呈明显的由上游方向向下游方向倾斜及厚度减低的特征。以上这些特征对于我们根据现在观察的浊流沉积推断古流域的形成环境、预测海底浊流沉积中的油藏等有着一定的参考价值。
[Abstract]:The research on the flow and sediment of turbidity current in bended channel has been one of the hotspots because of its close relationship with offshore oil and gas resources. At present, there are many difficulties and deficiencies in the field measurement and laboratory research. With the rapid development of computer technology. Three-dimensional numerical simulation is becoming more and more important in the study of turbidity flow. In this study, the Navier-Stokes equation based on Reynolds average, the k- 蔚 turbulence model modified by buoyancy terms and the orthogonal structural meshes are used in this study. Curvature (. 1.32. Three dimensional numerical simulation of turbidity flow and deposition or erosion in trapezoidal channel with gradient of 0.069 掳was carried out. It is found that the entrainment of the turbidity flow, secondary flow and sediment in a trapezoidal channel with a large curvature is strong as follows: (1) the entrainment of the fluid around the channel. The inclination of the density isosurface at the top section of the bend increases with the increase of the bending degree. (2) the exfoliation flow from the top of the upstream bend enters the downstream channel again, which makes the flow and deposition of the downstream more complicated; (3) there is a secondary flow in the outshore of the bottom of the channel, which is similar to a river with lower curvature. (4) there is erosion at the inner bank of the bend after the turbidite flow for many times, and the deposit at the bottom of the channel shows a wave-like tilt from the inner shore to the outer bank; (5) the deposits observed from the longitudinal section close to the edge of the curved channel are more undulating than those of the low curvature, and the trough exactly corresponds to the outside of the apex of the bend. 6) the deposits observed from the longitudinal section of the channel and the embankment except for the thin slope arched deposition interval with thicker channel bottom deposition. These characteristics are more obvious than those of low curvature channel, which are inclined from upstream direction to downstream direction and decrease in thickness. These characteristics can be used to infer the formation environment of paleo-basin based on the turbidite deposition observed now. It has certain reference value to predict the reservoir in the submarine turbidite deposition.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P736.21;P744.4

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