Multiphase Field-scale Modeling: Brine Transport

1. Multiphase Field-scale Modeling: Brine Transport Ann Cook Per Hatlevik Jonathan Levine Brice Loose Keegan Roberts Amber Sallerson Katy Schulte Martina Vlckova Thomas Willingham

2. Introduction to DNAPLs • Types • Sources • Behavior PCE, TCE, DCE, VC, CT, CF, DCM, TCA

3. Introduction to DNAPLs • Long lived • Difficult to remove • Health Hazards • Liver problems • Increased risk of cancer • Nervous system, or circulatory problems1

4. Brine Treatment Technology • How does it work? • Mobilization of the NAPL • Increase Gravimetric Forces • Decrease Capillary Trapping Forces

5. Brine Treatment Technology • sn-a = NAPL-aqueous interfacial tension • r =effective pore size • rn= NAPL density • ra= aqueous phase density • g = gravitational acceleration • l = characteristic length of NAPL pool in vertical direction

6. Area of Remediation Sheet-piles Impermeable Layer (e.g., clay) Plan View Profile View Brine Treatment Technology • How does it work? • Closed system on 5 sides

7. Brine Treatment Technology • How does it work? No Flow Boundary No Flow Boundary

8. Brine Treatment Technology • How does it work? Pump in Brine Layer

9. Brine Treatment Technology • How does it work? Lower Water Table

10. Brine Treatment Technology • Gravimetric Forces Removal of DNAPL

11. Brine Treatment Technology • How does it work?

12. Brine Treatment Technology • How does it work? Removal of DNAPL

13. Brine Treatment Technology • How does it work?

14. Brine Treatment Technology • How does it work? Remove Brine <1% Original DNAPL Mass

15. Brine Treatment Technology • How does it work? <1% Original = Meet DNAPL Mass Standards

16. Brine Treatment Technology • Why is it novel? • $$ Cheaper $$ • Higher rates of removal than current technologies Pump and Treat Natural Attenuation

17. Possible Instabilities in the System • Physical • Density (changes and/or differences) • Excessive Surfactant Concentration bypass • Pore Clogging • Model • Fingering • Gravity - Rayleigh

18. Rayleigh-Taylor Instability Brine • Initial density stratified domain • Unstable system (small perturbations) • Occur in model and physical system Ground Water

19. Rayleigh Number • Dimensionless Number • Ratio

20. Modified Rayleigh Number

21. SUTRA • Code written by USGS • Simulates single phase fluid flow and transport in the subsurface • Uses a combination of finite-element and finite difference methods to solve a series of equations

22. Conservation Equations • Species Balance Equation • Species-Summed Flow Equation

23. SUTRA Transport Math Magic

24. SUTRA Fluid Flow Species Summed Flow Equation Darcy’s Law Math Magic

25. Requirements for SUTRA DL < 4aL Pe < 2 • DL = local distance between sides of an element measured in the direction parallel to local flow • aL = longitudinal dispersivity

26. SUTRA Goal • To model a freshwater system where we inject brine • 3D model • Relatively small in the y-direction • Visualize system instabilities • Removal of brine from system

27. Simulations Ran • Brine slumping model • Fully saturated fresh water system with brine injection • Unsaturated brine injection • Multiple well configurations

28. Example Problem: Slumping brine interface High frequency spatial hydraulic conductivity which admits an analytic solution in the case that the vertical scale is much less that the horizontal (H << R), and a constant hydraulic conductivity (Kc)

29. Homogenization permits approximation of K(x,z,t) as a constant that captures the variability Homogenized equations compare well with the accepted numerical solution. High frequency variations are absent.

30. Evaluate Instabilities Injection Wells Extraction Well

31. Fingering Fingering due to viscous instability

32. SUTRA MODELINGBCs

33. SUTRA MODELINGInitial Injection

34. SUTRA MODELINGBrine Injection

35. Transport and Flow EquationsAKA “The Magic”