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Effects of capillary pressure and use of polymer solutions on dense, non-aqueous-phase liquid retention and mobilization in a rough-walled fracture

Journal Article · · Environmental Science and Technology
DOI:https://doi.org/10.1021/es980752h· OSTI ID:6428891
;  [1]
  1. Queen's Univ., Kingston, Ontario (Canada). Dept. of Civil Engineering

In this laboratory study, perchloroethylene (PCE) was permitted to migrate through a horizontal rough-walled limestone fracture under controlled conditions to assess fracture retention capacity. Retention of immiscible-phase PCE in the absence of an applied wetting-phase hydraulic gradient varied between 11% and 26% of the fracture volume. A portion of this residual could be removed through water flooding; however, even at the maximum applied hydraulic gradient of 1.0, residual PCE remained in the fracture. The observed correlation of reduced residual saturation with capillary number (N[sub c]) demonstrated that this rough-walled fracture exhibited behavior similar to that of a porous medium under water-flooding conditions. For a given hydraulic gradient, polymer-enhanced floods (using xanthan gum) were not as successful as conventional water flooding at removing residual from the fracture. The traditional form of the capillary number became an increasingly poor predictor of mobilization behavior as the viscosity of the displacing phase was increased. Incorporation of ([mu][sub w]/[mu][sub nw])[sup [minus]0.5] into the traditional capillary number provided a more appropriate dimensionless group with which to correlate residual PCE saturation in the fracture as [mu][sub w] increased.

OSTI ID:
6428891
Journal Information:
Environmental Science and Technology, Journal Name: Environmental Science and Technology Vol. 33:14; ISSN ESTHAG; ISSN 0013-936X
Country of Publication:
United States
Language:
English