基于图像分析方法研究柴油在多孔介质中的迁移与分布特征

Migration and Distribution Characteristics of Diesel in Porous Media Based on Image Analysis

为明确多孔介质性质对柴油迁移与分布特征的影响,利用图像分析方法对柴油在3种不同粒径多孔介质中的迁移与分布特征进行实验研究。结果表明,柴油在粗粒径石英砂中的垂向迁移速率更大,迁移锋面不稳定,指流更明显;污染面积、污染界面周长、垂向迁移距离与时间具有良好的线性关系,拟合系数(R^2)均在0.99以上;污染面积增长率、污染界面周长增长率、垂向迁移速率与石英砂粒径大小呈正相关;平均粒径、不均匀系数、曲率系数与柴油迁移与分布特征关系密切,且拟合方程得到的计算值和实验值差别很小,可用其近似表示实验值;相同入渗深度区域中,柴油在细粒径石英砂中的饱和度比在粗粒径石英砂中的高,而粗粒径石英砂污染面积约为细粒径石英砂污染面积的1/3左右。

To determine the effect of porous media on the migration and distribution of diesel,the migration and distribution characteristics of diesel in three porous media with different particle sizes were investigated by image analysis.Experimental results show that,compared with other two porous media,coarse-grained porous media can lead to the fastest diesel vertical migration rate.In addition,for coarse-grained porous media,it is found that the migration front is unstable with obvious finger flow.It has been noticed that,for the contamination area,contamination interface circumference and vertical migration distance,all of them have a good linear relationship with time,with correlation coefficients ( R 2) above 0.99.The growth rate of contamination area,the growth rate of perimeter of contamination interface and the vertical migration rate are proportional with the size of porous media.The average particle ( D 50 ),the uneven coefficient ( Cu ) and the curvature coefficient ( Cc ) are closely related to the migration and distribution characteristics of diesel,and their relationship can be quantitatively expressed by a linear equation.The difference between the calculated and experimental results is very minor,thus the calculated results can be used to represent the experimental data.In the same penetrating depth region,the diesel saturation in the fine-grained porous media is higher than that in the coarse-grained porous media,and the contamination area of the coarse-grained porous media is about 1/3 of that of fine-grained porous media.