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Advances in Computational Models of Subsurface Media: Past, Present, and Future

Explore the evolution of computational models for subsurface media from basic to advanced, covering flow, chemical transport, bio-geochemistry, and geomechanics. Discover groundbreaking models like AT123D and FEMWATER, used for groundwater regulation and environmental management. Learn about the significant contributions of HYDROGEOCHEM in chemical transport modeling. Engage with the latest numerical approaches and simulation techniques shaping the future of subsurface studies.

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Advances in Computational Models of Subsurface Media: Past, Present, and Future

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  1. Advances in Computational Models of Subsurface Media: Past, Present, and Future Gour-Tsyh Yeh (gyeh@ncu.edu.tw) Graduate Institute of Applied Geology National Central University Jhongli, Taoyuan 32001 TAIWAN Presented at Earth Science-2015: 4th International Conference on Earth Science and Climate Change Hotel Melia Alicante, Alicante, Spain, June 16-18, 2015 1

  2. Introduction • Media • Simple homogeneous isotropic to complicated heterogeneous, anisotropic media • Processes • Flow: Simple saturated to variably saturated, multiphase • Chemical Transport: Single species to multi-species, multi-component • Bio-geochemistry: Simple ad hoc to reaction-based approach • Thermal: Simple isothermal to non-isothermal approach • Geomechnaics: Elastic, viso-elastic, plastic, viso-elastic-plastic materials • Computation • Exact Solution: Analytical to semi-analytical solutions • Numerical Approaches: FEM, FDM, FVM, special methods

  3. Advances In the Past • 1960’s and Earlier:Analytical Flow and Solute Transport Models in Saturated Zones or Unsaturated Zones. • 1970’s:Single Phase Flow and Solute Transport Models in Saturated Zones or Vdose Zones. • 1980’s:Variably Saturated Flow, Two or Three Phase Flow. Coupled Flow and Solute Transport in Saturated Zone or Vadose Zone. Reactive Transport in Saturated Zone or Variably Saturated Media. • 1990’s:Coupled Flow and Solute Transport in Variably Saturated Media.Coupled Single Phase Flow, Thermal Transport, and Reactive Transport in Saturated Zones, Unsaturated Zones, or Variably Saturated Media. • 2000’s:Coupled Two or Three Phase Flow, Thermal Transport, and Reactive Transport.

  4. Over 100 groundwater models have been developed

  5. Only three models stand out • AT123D:Analytical Transient One , Two , and ThreeDimensional Simulations of Waste Transport in the Aquifer System. • GMS-FEMWATER:A Three-Dimensional Finite Element Model for Simulating Density-Dependent WATER Flow and Transport in Variably Saturated Media. • HYDROGEOCHEM: A Coupled Model of Fluid Flow, Thermal Transport, and HYDROGEOCHEMical Transport through Saturated Unsaturated Media.

  6. AT123D: One of the most widely used analytical models for groundwater plume delineation • One of the most general and widely used analytical models. It has been marketed by many consulting companies and many training courses have been conducted by these companies. • Use Google Search “AT123D New Jersey”, you find: Guidance for Using the SESOIL and AT123D Models to Develop Site Specific Impact to Ground Water Soil Remediation Standards ... • In fact, EPA, API, and more than 20 states in USA have the similar guidelines to use AT123D in conjunction with SESOIL • Five dollars make you rich ($5 x 1,000 x 365 x 24 = $44 Millions)

  7. How AT123D has been used for regulation

  8. FEMWATER: Used Worldwide • Among the very first well-documented subsurface models to integrate vadose and groundwater zones

  9. Environmental setting where FEMWATER can be employed

  10. 1:Aquifer storage and recovery (ASR) using FEMWATER

  11. Animation of Total Head: totalhead_unsym.avi Marco Island System Bob Verrastro, 2012 Lower East Coast, Water Supply Plan Update, Workshop #3, June 19, 2012 • Largest ASR system in the SFWMD • 7 wells, 9 MGD capacity, since 1997 • Arsenic not a problem • 1.7 billion gallons currently stored • Pump treated surface water to ~750’ deep – sandy portion at top of Floridan aquifer

  12. Animation of Concentration: Concentration.avi Marco Island System Bob Verrastro, 2012 Lower East Coast, Water Supply Plan Update, Workshop #3, June 19, 2012 • Largest ASR system in the SFWMD • 7 wells, 9 MGD capacity, since 1997 • Arsenic not a problem • 1.7 billion gallons currently stored • Pump treated surface water to ~750’ deep – sandy portion at top of Floridan aquifer

  13. 2. Application of FEMWATER to Mitigating a Dredging Site Model domain (left) and subsurface data point location (right)

  14. Simulated contour of 0.001 ppt salinity (blue lines) at various times Motsu_con.avi Proper mitigations (e.g., slurry walls in combination with pumping) could contain the salt with the disposal facility, DA2

  15. Legend Slurry Wall Location Surface of Bad Trash Water Table Surface 3: Model of Injection Gallery BlanketI_New.avi Location of Unsaturated Trash Trash (Kh = 1.0 ft/day Kv = 0.5 ft/day) Backfill (Kh = 0.5 ft/day Kv = 0.1 ft/day) Revised Blanket Configuration Injection in Blanket Only (80 gpm) No Extraction

  16. HYDROGEOCHEM:Widely used by government agencies and academia • Aqueous complexation and precipitation-dissolution models (Westall et al., 1976) • Adsorption-desorption processes and models (Davis and Leckie, 1978) • Ion-Exchange (Al Valocchi, et al., 1981) • Among the first generic reactive chemical transport models to include aqueous complexation, precipitation-dissolution, adsorption-desorption, ion-exchange, redox, and acid-base reactions – Dawn of HYDROGEOCHEM Era (Yeh and Tripathi, 1990)

  17. Environmental setting for HYDROGEOCHEM Simulations

  18. Applications with HYDROGEOCHEM 5.0 (A THC Process Model) • Variably Saturated Flow (H) • Thermal Transport (T) • Reactive Transport of N reactions among M Species [C(R)] • T, H, or C Modeling • TH, TC, or HC Modeling • THC Modeling

  19. Variably Saturated Flow Problem Description Initial and Boundary Conditions for Variably Saturated Flow Kxx = Kyy = Kzz = 1 dm/day Kxy = Kxz = Kyz = 0 dm/day.

  20. Pressure Field and Flow Animation Steady-state pressure head Velocity fields along cross-section x = 0 Velocity.avi

  21. T=298oK T=308oK T=298oK Initial Condition: T=298oK Thermal Transport Description Initial and Boundary Conditions for Thermal Transport Specific Heat: Cw = 1.0E20 dm2/day2/oK Cm = 1.0E19 dm2/day2/oK Thermal conductivity: = 1.0E19 dm2/day2/oK

  22. Animation of Temperature Temperature.avi Animation of Temperature Contours for Thermal Transport

  23. Reactive Transport Description (1) Reaction Network of Various Types (33 reactions, 41 Species)

  24. Reactive Transport Description (2) Reaction Network of Various Types (33 reactions, 41 Species) * This users’ specified equation is modified from Stumm and Morgan, 1996, in which SA is the unit surface area (m2 g-1) of mineral, NS is the surface site density (mol sites m-2), NA is Avogadro’s number (mol sites per mol), Mmineral is the molecular weight of mineral &The species H2O can be decoupled from the system if its activity is assumed 1.0.

  25. Reactive Transport Description (3) Initial and Boundary Conditions for Reactive Transport

  26. Reactive Transport Description (4) Initial Conditions

  27. Reactive Transport Description (5) Boundary Conditions

  28. Animation of Species S1: S1.avi M (Fe(OH)3(s)) S1 (FeOH) (R2); Fe(OH)3(s) ↔ Fe3+ - 3 H+(R1)

  29. Animation of Species C10: C10.avi C1 + C5 C10 ; Log k7f = 25.00, Log k7b = -2.57 (R7) Fe3+ + EDTA4- ↔ FeEDTA-

  30. Further Advances: Present and Future THMC:Thermal-Hydraulic (Hydrology)-Mechanic-Chemical Processes • Multiphase flow(aqueous phase, gaseous phase, and super liquid phase, NAPL, etc.) • Thermal Transport(temperature changes induced by fluid injection, associated phase changes and chemical reactions) • Geo-Mechanics(how faults and fractures affect fluid pressure and chemical migration, and the converse of fluid pressure inducing rock deformation and fault displacement) • Reactive Transport(subsurface biogeochemical reactions among chemicals, groundwater/brine, and rock) [aqueous complexation, adsorption-desorption, ion-exchange, precipitation-dissolution, redox, acid-base reactions, microbial-mediated redox, nutrient cycle, carbon cycle, biota kinetics, metal cycle, etc.]

  31. Environmental setting for Multiphase Flow System

  32. Multiphase Flow Module Example:Heterogeneous Media,Pumping, and injecting wells

  33. Animation: Case3_Sw.avi, Case3_Sn.avi, Case3_Sa.avi Time= 0~ 3 day S1 S2 S3

  34. Geomechanical Module Example: instability of a two layered solid body – well known as salt diapirism.

  35. Deformation initially and at equilibrium for the viscous problem

  36. Animation for the viscous problem: Viscous.avi

  37. A THMC Model – HYDROGEOCHEM 6.0, 6.1, 7.0 and 7.1

  38. A THMC Model – HYDROGEOCHEM 6.0 • Any Number of Phase Flow • Thermal Transport • Reactive Transport of Any Number of Reactions among Species • Geo-Mechanical Deformation of Visco-Elastic Materials • All Four Modules Are Explicitly Coupled via Storage Coefficients and/or Capillary Pressure Induced Diffusion

  39. Coupled Processes Modeling with HYDROGEOCHEM 6.0 – Problem Description (1) • 3 Phase Flow • Thermal Transport • Geo-mechanical Deformation Due to Multi-phase Flow and Reactive transport • Reactive Transport of 40 Species Subject to 28 Reactions

  40. Coupled Processes Modeling with HYDROGEOCHEM 6.0 – Problem Description (2) • Radioactive wastewater containing high concentration of NpO2+ is injected into a three fluid phase (water, NAPL, and air) system. • Thermal effects are included. • Injection effects on geo-mechanics (porosity change and deformation) are considered. • Media contain high adsorption sites in Region A. • Chemistry includes intra phase (homogeneous) reactions and inter phase (heterogeneous) reactions

  41. Coupled Processes Modeling with HYDROGEOCHEM 6.0 – Problem Description (3) Reaction Network: 28 reaction, 40 species

  42. Coupled Processes Modeling with HYDROGEOCHEM 6.0 – Problem Description (4) Reaction Network: 28 reaction, 40 species

  43. Coupled Processes Modeling with HYDROGEOCHEM 6.0 – Problem Description (5) Reaction Network: 28 reaction, 40 species

  44. Coupled Processes Modeling with HYDROGEOCHEM 6.0 – Problem Description (6) Initial and Boundary Conditions for Multiphase Flow

  45. Coupled Processes Modeling with HYDROGEOCHEM 6.0 – Problem Description (7) Initial and Boundary Conditions for Thermal Transport

  46. Coupled Processes Modeling with HYDROGEOCHEM 6.0 – Problem Description (8) Initial and Boundary Conditions for Reactive Chemical Transport

  47. Coupled Processes Modeling with HYDROGEOCHEM 6.0 – Problem Description (9) Initial and Boundary Conditions for Geo-mechanics Simulation

  48. Coupled Processes Modeling with HYDROGEOCHEM 6.0 – Problem Description (10) Mesh and Numerical Parameters • A uniform mesh of 1,485 nodes and 1,408 elements • Total simulation time: 2.985 days • Initial time step size = 0.0001 day • Maximum time step size = 0.001 day • Total time steps: 3,000 48

  49. Coupled Processes Modeling with HYDROGEOCHEM 6.0 – Problem Description (11) Contour of degree of saturation for the aqueous phase Water coming to the simulated region displaces other two phases.

  50. Coupled Processes Modeling with HYDROGEOCHEM 6.0 – Problem Description (12) Contour of degree of saturation for the NAPL phase NAPL is displaced by the injection water and moves downward

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