Experimental and computational investigations of subsurface heterogeneity and contaminant distributions in complex geologic media

地下在多个尺度上是不均匀的，这是规律而不是例外。关于流动和输运参数的空间变异性的信息通常是通过对小规模测量进行地质统计分析获得的。尽管地质统计学方法被广泛使用，但目前尚不清楚它是否能够保护地质特征、其连通性和形态，而这些特征可能对流体流动产生重大影响，更重要的是对污染物迁移产生重大影响。我们最近取得了显着的进展，映射水力传导率（K）和特定的存储（Ss）的异质性使用水力层析成像。水力层析成像包括从封隔层中顺序抽水，并相应地监测附近钻孔中跨隔器系统中的水头变化信息。以层析成像方式抽取和收集水头变化数据，可以获得关于压力变化从各个方向通过含水层传播的信息。然后将该信息用于计算K和Ss断层图像的随机逆模型中。水力层析成像实验表明，我们的小组在实验室进行的，它可以成像的K和Ss的分布以及它们的连通性大大优于克里金。该方法最近已扩展到包括分区示踪剂运输信息图像的位置的致密非水相液体（DNAPL）饱和度在3-D。初步结果表明，DNAPL饱和度和他们的池可以准确地成像。对源区DNAPL饱和度的准确成像将大大提高我们对加拿大及其他地区数千个地点进行补救的能力。拟议的研究重点是进行补充实验和计算调查，应显着提高我们的能力，以映射地下异质性和污染物源区在复杂的地质介质。这些能力的发展也将使我们能够显着推进我们的流动和运输过程的基本理解，在这样的媒体。

The subsurface is heterogeneous at multiple scales and this is the rule rather than the exception. Information about spatial variability of flow and transport parameters is most commonly obtained through geostatistical analysis of small-scale measurements. Despite its common use, it is unclear whether the geostatistical approach can preserve geological features, their connectivity and morphology which can have large impacts on fluid flow and more importantly, contaminant transport. We have recently made significant strides in mapping hydraulic conductivity (K) and specific storage (Ss) heterogeneity using hydraulic tomography. Hydraulic tomography involves the sequential pumping of water from packed-off intervals and the corresponding monitoring of head change information in straddle-packer systems in nearby boreholes. Pumping and collection of head change data in a tomographic manner allows one to obtain information on the propagation of pressure changes through the aquifer from various directions. This information is then used in a stochastic inverse model that computes K and Ss tomograms. Hydraulic tomography experiments performed in the laboratory by our group show that it can image the distributions of K and Ss as well as their connectivity considerably better than kriging. The approach has been recently extended to include partitioning tracer transport information to image the locations of Dense Nonaqueous Phase Liquid (DNAPL) saturations in 3-D. Preliminary results show that DNAPL saturations and their pools can be imaged accurately. Accurate imaging of DNAPL saturations in source zones will considerably improve our abilities to remediate thousands of sites in Canada and beyond. The proposed research focuses on conducting complementary experimental and computational investigations that should significantly advance our capabilities to map subsurface heterogeneity and contaminant source zones in complex geologic media. Development of these capabilities will also allow us to significantly advance our fundamental understanding of flow and transport processes in such media.