Contaminant Transport Through Single Fracture With Porous Obstructions

Abstract

Transport of contaminant through a single fracture, modeled as a closely spaced parallel plates aperture, is analyzed theoretically and numerically. Permeable contact regions between the plates are modeled as fixed packs of homogeneous, isotropic, and inert porous material. A nondimensional theoretical expression for estimating the equivalent global permeability of the aperture is presented in terms of the relative volume occupied by the contact regions. Transient transport of contaminant (solute) through this heterogeneous system is analyzed considering injection of fluid with uniform concentration at the inlet of the fracture. For natural systems, it is verified that relative volume and distribution of contact regions affect clean-up time, defined as the time necessary for the complete removal of contaminant, only indirectly by varying the equivalent permeability of the system, otherwise their effect is negligible. The clean-up time of a clear (of contact regions) fracture, is correlated with the Peclet number for 10−1 ≤ Pe ≤ 106 .