Demonstration of the Capability of Mobility-Controlled-Flooding Technology to Overcome Heterogeneity Induced Bypassing in Subsurface Remediation (PNNL LDRD #90001
Overcoming Heterogeneity Induced Bypassing)
EMSL Project ID
11992
Abstract
IntroductionHeterogeneity induces bypassing of low-permeability zones in subsurface fluid flooding operations for remediation purposes. The contaminant in the bypassed areas is therefore untouched by the remedial fluid, which can prolong the remediation operations significantly. A PNNL Laboratory Directed Research and Development (LDRD) project proposal was approved to demonstrate that a mobility-controlled-flooding technology can be applied in the subsurface remediation to accomplish a complete sweep of the heterogeneous system, so that to significantly enhance the remedial efficiency. This technology forces injected remedial fluids into the otherwise bypassed low-permeability flow paths by controlling the mobility of the fluids by adding polymers to the fluids. Application of this new technology to subsurface cleaning up will enhance PNNL’s environmental remediation capability. Two dimension (2-D) flow cell experiments were proposed for the purpose of this project. It is now proposed that the 2-D flow cell experiments to be performed in the Subsurface Flow & Transport Experimental Laboratory (SFTEL) in EMSL.
The objectives of this proposed research include: to preliminarily develop a mobility-controlled-flooding technology for subsurface cleaning up, and to demonstrate the capability of the mobility-controlled-flooding technology in sweeping low permeable zones and enhancing remedial efficiency using the two dimensional (2-D) flow cell experiments.
Research Design and Methodology
A water soluble polymer will be selected based on literature. Flushing tests will then be conducted in a 2-D cell to demonstrate that the mobility control technology can be applied to improve remediation efficiency. A favorable mobility ratio and injection procedure will be used. The permeability contrast between the packed sand layers/lenses and flow rate on the sweep efficiency will also be investigated. The main tasks of this project are described in the following:
Task I – Demonstration of Complete Sweeping of Heterogeneous Formations
Quartz sand (Ottawa sand) with different particle sizes will be used to pack the sand box to generate layers and/or lenses to introduce heterogeneity. Packed sand box will be initially saturated with DI water. First, water flood will be performed to show heterogeneity induced bypassing to low-permeability layers/lenses. Sand box will then be flushed with a polymer modified solution to demonstrate the complete sweeping of the sand pack. A dye will be applied to both the water flood and the polymer flood so that the fluid fronts can be visualized and traced.
The heterogeneity contrast effects and the mobility ratio effects on the sweep efficiency will be tested. Different permeability distribution patterns and permeability contrast of packing will be applied in the sand box. The packed sand formation will be flooded with a set of polymer solution with a range of viscosities so that the optimum mobility ratio can be determined.
Task II – Demonstrate Improved Remediation Efficiency and NAPL Recovery from Heterogeneous System
In this task, NAPL will be placed in a heterogeneous system at residual saturation state in the 2-D flow cell. Surfactant containing remedial fluids with or without polymer addition will then be flushed through the cell. It will be shown that with mobility-controlled-flooding, NAPL recovery from the heterogeneous system is considerably higher. The NAPL saturation detection system in the SFTEL will be applied in the tests.
Expected Output
With successfully conducting the designed experiments in the SFTEL in EMSL, it is fully expected that a journal publication will be produced.
Abstract for FY06:
Enhanced Amendment Distribution in Subsurface Remediation
(PNNL FY2006 LDRD Project Proposal)
Lirong Zhong, Mart Oostrom, Tom Wietsma, Kirk Cantrell
Low-permeability zones in soil are bypassed when remedial fluids are injected into subsurface heterogeneous aquifer systems. The contaminant in the bypassed areas is, therefore, untouched by the amendments in the remedial fluid, which can significantly prolong the remediation operations. In this proposed project, the mobility-controlled flood (MCF) technology, which has been demonstrated to significantly improve the sweeping efficiency in heterogeneous systems, will be applied to enhance the remedial amendments delivery to the low permeability zones. Polyphosphate will be the specific remedial amendment used in this project. Investigation of the enhanced delivery of polyphosphate to the low permeable zones in the aquifer beneath the 300 Area at the U. S. Department of Energy (DOE) Hanford Site will be the focus of this research.
A water-soluble polymer will be used to modify the viscosity of the amendment-added remedial solutions. Batch experiments will be conducted to select the polymer-amendment solution. Two-dimensional (2-D) flow cells packed with heterogeneous systems similar to the ones in the Hanford Site 300 Area aquifer will be applied for the flow cell experiments to develop an injection protocol for the enhanced delivery. The 2-D flow cell experiments will be performed in the Subsurface Flow & Transport Experimental Laboratory (SFTEL) in the Environmental and Molecular Sciences Laboratory (EMSL).
Project Details
Project type
Exploratory Research
Start Date
2006-02-06
End Date
2007-06-07
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Zhong, L., et al., Enhanced remedial amendment delivery through fluid viscosity modifications:
Experiments and numerical simulations, J. Contam. Hydrol. (2008), doi:10.1016/j.jconhyd.2008.07.007
Zhong, L., M. Oostrom, T.W. Wietsma, M.A. Covert. 2008. Enhanced remedial amendment delivery through fluid viscosity modifications: experiments and numerical simulations. Journal of Contaminant Hydrology, In press.