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Enhanced remedial amendment delivery through fluid viscosity modifications: experiments and numerical simulations
L Zhong1, M Oostrom, T W Wietsma
1Energy and Environment Directorate, Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA 99354, USA. lirong.zhong@pnl.gov
Journal of Contaminant Hydrology
|September 13, 2008
Summary
Using xanthan gum, a shear-thinning polymer, enhances remedial fluid delivery to low-permeability zones in heterogeneous aquifers. This improves contaminant cleanup efficiency and stabilizes fluid fronts during subsurface remediation.
Area of Science:
- Environmental Science
- Geochemistry
- Chemical Engineering
Background:
- Low-permeability zones in heterogeneous aquifers are often bypassed during remediation.
- Bypassed contaminants prolong cleanup operations and increase remediation costs.
Purpose of the Study:
- To investigate the use of a shear-thinning polymer (xanthan gum) to improve remedial fluid access to low-permeability zones.
- To evaluate the impact of polymer concentration, injection rate, and permeability contrast on remediation efficiency.
Main Methods:
- Conducted eleven 2D flow cell experiments using xanthan gum, sodium mono-phosphate, and surfactant MA-80.
- Modified the Subsurface Transport over Multiple Phases (STOMP) simulator to incorporate shear-thinning effects.
- Analyzed fluid displacement behavior and amendment delivery to low-permeability zones.
Main Results:
- Xanthan gum significantly enhanced the delivery of remedial amendments to low-permeability zones.
- Increased sweeping efficiency was observed with the use of the polymer.
- Polymer addition stabilized the displacing fluid front, especially when density differences were present.
Conclusions:
- Shear-thinning fluids, like xanthan gum solutions, are effective in improving remediation of heterogeneous subsurface systems.
- The modified STOMP simulator accurately predicts experimental results and can be used for larger-scale remediation predictions.
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