二维孔隙介质中重非水相液体饱和度测定与分析

在二维均质饱和孔隙介质中利用光透法与高密度电阻率法定量监测重非水相液体(DNAPL)的运移过程与饱和度。 将光透法与高密度电阻率法相结合,进行高密度电阻率法对 DNAPL 在饱和多孔介质中渗流过程的定量监测。在二维砂箱 中进行 DNAPL 的入渗试验,应用光透法与高密度电阻率法进行动态监测,分别利用 CCD 相机、LCR 数字电桥采集数据。 光透法的数据处理采用“水-DNAPL”两相中 DNAPL 饱和度的计算公式。而高密度电阻率法的数据处理是将获得的电阻值 数据转化为电阻率值,然后利用 Archie 公式获得重非水相液体的饱和度空间分布。Archie 公式中参数β值本文采用与光透法 相结合的新方法来获取,克服了传统方法获取β值时存在的困难。根据不同时刻的饱和度空间分布可以估算注入砂箱内的 DNAPL 总量,并将其与实测的入渗量进行对比。结果表明,与光透法结合后的高密度电阻率成像法能定量监测饱和孔隙介 质中 DNAPL 的入渗过程,且估算的 DNAPL 入渗量与实测值比较吻合,提出的基于光透法计算β值的新方法是有效且可行的。

DNAPL Saturation Measurements and Analysis in 2-D Porous Media

Light transmission visualization (LTV) and electrical resistivity tomography (ERT) methods are used to quantify dense non-aqueous phase liquids (DNAPL) saturation in a two-dimensional (2-D) sand box with two fluid phase systems of water and DNAPL. The media are uniform and saturated. Infiltration experiment of DANPL is conducted in the 2-D sand box. Meanwhile, Charged Coupled Digital (CCD) camera and LCR Digital Bridge are used to monitor the movement of DNAPL. The LTV model is applied to calculate the saturation of DNAPL in this study. To get the spatial distribution of DNAPL saturation in ERT method, one needs to transform the resistance to resistivity, and then use the empirical formula “ Archie Formula”. A new method was proposed to calculate the value of β, which is the only parameter in “Archie Formula”. The new method is much simpler and more convenient in comparison with the traditional ways. The amounts of DNAPL infiltration are calculated based on the spatial distribution of DNAPL saturation at different times, which agree with the observations well. The experiment results show that ERT method coupled with LTV method could quantitatively monitor the migration of DNAPL in saturated porous media, and the new method to obtain the value of β is applicable.