Description

Industry throughout the world uses large quantities of organic liquids. These byproducts of the industrial process represent the most common type of soil and groundwater pollutants. Dense nonaqueous phase liquids (DNAPLs) such as chlorinated solvents are among the most frequently encountered and serious types of organic contaminants. Many conventional remediation techniques have proven to be unsuccessful or of limited success in remediating soil and groundwater contaminated by DNAPL. Active research models promise technology that avoids at least some of the problems and limitations of many existing remediation methods. However, none of these models account for the effects of surfactant on interfacial tension (IFT), surfactant phase behavior, capillary number, or surfactant adsorption. UTCHEM can be used to simulate a wide range of displacement processes at both the fields and laboratory scales. The model is a multiphase, multi-component, three-dimensional finite-difference simulator. The model was originally developed to model surfactant enhanced oil recovery, but modified for applications involving the use of surfactant for enhanced remediation of aquifers contaminated by NAPLs. The balance equations are the mass conservation equations, an overall balance that determines the pressure for up to four fluid phases, and an energy balance equation to determine the temperature. The number of components is variable depending on the application, but would include at least surfactant, oil, and water for surface enhanced aquifer remediation (SEAR) modeling. When electrolytes, tracers, co-solvents, polymer, and other commonly needed components are included, the number of components may be on the order of twenty or more. When the geochemical option is used, a large number of additional aqueous components and solid phases may be used.

Benefits

• Demonstrates accurate physical and chemical property models
  
• Does not have limits of current technology and therefore accounts for effects on surfactants on interfacial tension, surfactant phase behavior, capillary trapping, and surfactant adsorption
  
• Can be used to design the most efficient surfactant remediation strategies, taking into account realistic soil and fluid properties

Features

• 3-dimensional, variable temperature
  
• IMPES-type formulation
  
• Third-order finite difference with a flux limiter
  
• Four phase (water, oil, micro emulsion, and gas)
  
• Vertical and horizontal wells
  
• Constant pressure boundaries
  
• Cartesian, radial, and curvilinear grid options
  
• Heterogeneous permeability and porosity
  
• Full tensor dispersion coefficient and molecular diffusion
  
• Adsorption of surfactant, polymer, and organic species
  
• Solubilization and mobilization of oil
  
• Clay/surfactant cation exchange
  
• Water/surfactant (cosolvent)/oil phase BehaviorPolymer with non-Newtonian rheology Tracers (partitioning, reaction, adsorption, and radioactive decay) Compositional density and viscosity functionsSurfactant/foam modelMultiple organic propertiesTrapping number including both viscous and buoyancy forcesDual porosity model for tracerGeochemical reactionsBiological reactionsSeveral polymer/gel kineticsEquilibrium and rate-limited organic dissolutionRock dependent capillary pressure and relative permeabilityBrooks-Corey
  

Market Potential/Applications

Oil field applications include tracer tests to characterize both single- and dual-porosity oil reservoirs, surfactant EOR including the use of polymers and foam, polymer flooding for EOR, high pH chemical flooding for EOR, microbial EOR, profile control of oil wells with polymer gels, and modeling formation damage of oil wells. Groundwater applications include infiltration of NAPL in both saturated and unsaturated zones, partitioning inter-well tracer tests (PITTs) in both saturated and unsaturated zones, and remediation using surfactants (SEAR) and/or polymers, surfactant foam, or cosolvents.

Contact:

University of Texas,
Austin, USA
Website : www.otc.utexas.edu