Characterization of Bulk Fluid and Transport Properties for Simulating Polymer-Improved Aquifer Remediation

Abstract

In situ mobility reduction resulting from the addition of water-soluble polymers to subsurface remedial fluid formulations has the potential to significantly improve the delivery and subsurface distribution of remediation agents within heterogeneous contaminated aquifer systems. However, the increased viscosity, non-Newtonian rheology, competing retention and acceleration mechanisms, and the potential for these fluids to reduce media permeability because of mechanical filtration of these large polymer molecules complicate treatment design calculations and often necessitate numerical simulation for purposeful evaluation and application of this technology. In this paper, laboratory and computational methods are presented that were used to characterize bulk fluid and porous media transport properties of xanthan gum biopolymer-amended fluids for the purpose of facilitating numerical simulation. A detailed discussion of polymerized fluid transport mechanisms and input parameters for simulating polymer transport using the University of Texas Chemical Composition (UTCHEM) simulator is provided. The simulator was used to validate the independently derived input parameters against the results of a five-layer, two-dimensional (2D) sand tank experiment. An overall 74% improvement in sweep efficiency was observed for the polymer-amended fluid within this sand pack, relative to the nonamended case.