Solute transport in heterogeneous sediments: experimental and
theoretical investigations
Abstract
Abstract: Heterogeneity is crucial for predication of flow and
contaminant transport in subsurface formations. To characterize the
heterogeneous architecture, the relationship between multimodal
correlation of hydraulic conductivity (K) and plume dispersion is
investigated through integration of experimental, theoretical, and
numerical simulation approaches. The spatial correlation structure of K
in a heterogeneous sedimentary column is investigated by analyzing the
covariance components and transition probability structures. The
detailed sedimentary facies data of the column ensures the accuracy of
heterogeneous sediment characterization. Lagrangian-based transport
models were developed to estimate solute dispersion in non-reactive
tracer injection experiments. The results show that the model
successively predict the solute transport when the spatial correlation
structure is well-defined. Dispersivity estimated by the
Lagrangian-based model slightly larger than those obtained from the
measurements of tracer experiments. Further, the upscaled dispersivity
that derived from transition probability is dominated determined by the
cross-transition probability structure, while the contribution of
auto-transition terms are quite small. The contribution of the
cross-transition terms increases with the increasing contrast in mean
permeability between different facies. Numerical modeling results
confirm that upscaled dispersivity values well capture solute
breakthrough behavior along the heterogeneous sediment column. Keywords:
Solute transport; Dispersion; Dispersivity; heterogeneity; porous media;
Sedimentary structure; Column experiment; Lagrangian-based model.