Here, we investigate large scale particle motion and solute breakthrough in sparse three-dimensional discrete fracture networks (DFN) characterized by power-law distributed fracture lengths. The three networks we consider have the same fracture intensity values but exhibit different percolation densities, geometric properties and topological structures. We considered two different average transport models to predict solute breakthrough, a streamtube model and a Bernoulli CTRW model, both of which provide insights into the flow fields within the networks. The streamtube model provides acceptable predictions at short distances in two of the networks, but fails in all cases to predict breakthrough times at the outlet plane, which indicates that particle motion in such fracture networks cannot be characterized by a constant velocity between the inlet and control plane at which the breakthrough curve is detected. Rather the structure of the network requires that frequent velocity transitions be made as particles move through the system. Despite the relatively broad distribution of fracture radii and relatively small number of independent velocity transitions, the CTRW approach conditioned on the initial velocity distribution provides reasonable predictions for the breakthrough curves at different distances from the inlet. The application of these averaged transport models provides a richer understanding of the link from the fracture network structure to ow and transport properties.
Hyman, Jeffrey De'Haven, Dentz, Marco, Hagberg, Aric Arild, & Kang, Peter K. (2019). Linking structural and transport properties in three-dimensional fracture networks. Journal of Geophysical Research. Solid Earth, 124(2). https://doi.org/10.1029/2018JB016553
@article{osti_1492671,
author = {Hyman, Jeffrey De'Haven and Dentz, Marco and Hagberg, Aric Arild and Kang, Peter K.},
title = {Linking structural and transport properties in three-dimensional fracture networks},
annote = {Here, we investigate large scale particle motion and solute breakthrough in sparse three-dimensional discrete fracture networks (DFN) characterized by power-law distributed fracture lengths. The three networks we consider have the same fracture intensity values but exhibit different percolation densities, geometric properties and topological structures. We considered two different average transport models to predict solute breakthrough, a streamtube model and a Bernoulli CTRW model, both of which provide insights into the flow fields within the networks. The streamtube model provides acceptable predictions at short distances in two of the networks, but fails in all cases to predict breakthrough times at the outlet plane, which indicates that particle motion in such fracture networks cannot be characterized by a constant velocity between the inlet and control plane at which the breakthrough curve is detected. Rather the structure of the network requires that frequent velocity transitions be made as particles move through the system. Despite the relatively broad distribution of fracture radii and relatively small number of independent velocity transitions, the CTRW approach conditioned on the initial velocity distribution provides reasonable predictions for the breakthrough curves at different distances from the inlet. The application of these averaged transport models provides a richer understanding of the link from the fracture network structure to ow and transport properties.},
doi = {10.1029/2018JB016553},
url = {https://www.osti.gov/biblio/1492671},
journal = {Journal of Geophysical Research. Solid Earth},
issn = {ISSN 2169-9313},
number = {2},
volume = {124},
place = {United States},
publisher = {American Geophysical Union},
year = {2019},
month = {01}}
Hyman, J. D.; Jiménez-Martínez, J.; Viswanathan, H. S.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 374, Issue 2078https://doi.org/10.1098/rsta.2015.0426