Ensure a Secure and Sustainable Energy Future

Basin-scale Density-dependent Groundwater flow Near a Salt RepositoryKristopher L. KuhlmanSandia National Laboratories

Anke Schneider Gesellschaft fr Anlagen- und Reaktorsicherheit

Washington, DCSeptember 7-9, 2016

Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energys National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND2016-8647 C

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OutlineGeologic/Hydrologic Background2016 progressSNLGRSSummary of issuesGoals moving forward

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WIPP HydrogeologyRepository in Salado bedded salt formation>500-m thick salt unitHydrogeology of formations above saltRustler FormationCulebra dolomiteMagenta dolomiteAnhydriteMudstone/HaliteDewey Lake Red BedsSilt/sand stones + clayDockum GroupSilt/sand stones + clay

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Rustler Conceptual Model4

West(Nash Draw)EastWest of WIPPShallow unitsHigh permeabilityRelatively fresh waterEast of WIPPDeeper unitsLow permeabilitySaturated brineRegional groundwaterFlow used in WIPP PALong-term geological stability of salt

Corbet (2000) WIPP Model5Most of Delaware BasinTransient SimulationClimate variation (dry vs. wet)14,000 y present 10,000 yModel Implementationwater table moving boundary model~8700 km2 region (78 km 112 km)Coarse mesh (2 km square cells)12 model layers (10 geo layers)1,500 cells/layer~18,000 elements total

Motivation6Benchmark against existing solution (Corbet, 2000)Comparison with original modelOld mesh, model parameters & boundary conditionsInclude new processes, features & dataInclude density-driven flow (e.g., Davies, 1989)Include chemistry & mineral dissolutionInvestigate flow & chemistry boundary conditionsTest and update hydrogeological conceptual modelIncoporate current data: 81Kr GW age data, water level dataComparison and Development of Models PFLOTRAN (SNL)Add density dependent flowd3f (GRS)

SNL Progress in 20167

SNL PFLOTRAN version8

Corbet (2000): Hydraulic conductivity [m/s]PFLOTRAN: Permeability [m2]

SNL PFLOTRAN version9

~25x vertical exaggeration

SNL PFLOTRAN version10

Original Mesh: 13-layer hexahedral (cuboid) elements (18,000 elements)100x vertical exaggeration

SNL PFLOTRAN model11

Without density dependence or chemistry

SNL PFLOTRAN model12

GRS Progress in 201613

SNL: data of basin-scale groundwater model after Corbet & Knupp 1996raster data of 10 hydrogelogic units Basin-scale model df++14

df++

source: SNL, SECOFL3D

df++ model

Dewey Lake/TriassicAnhydrite 5Mudstone/Halite 4Anhydrite 4Magenta DolomiteAnhydrite 3Mudstone/Halite 3Anhydrite 2Culebra DolomiteLos Medanos Member110 km 500 m

N 6,000 km

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df++ model

Dewey Lake/TriassicAnhydrite 5Mudstone/Halite 4Anhydrite 4Magenta DolomiteAnhydrite 3Mudstone/Halite 3Anhydrite 2Culebra DolomiteLos Medanos Member110 km 500 m

N 6,000 km16

anisotropic grid refinementadapt multigrid operators

df++ prism grid

N

source: Corbet 2000last year: 2,614,000 tetrahedrons (coarse grid)now: 54,228 prisms (coarse grid) 18,000 hexahedrons SECOFL3D17

Dewey Lake/TriassicAnhydrite 5Mudstone/Halite 4Anhydrite 4Magenta DolomiteAnhydrite 3Mudstone/Halite 3Anhydrite 2Culebra DolomiteLos Medanos Member

Free Water Table levelset method

18model domain D (const.)phreatic surface represented by a levelset function

partially saturated zone (not solved here)

fully saturated zone (Darcys law)

groundwater table (moving boundary)(t)(t)D\(t)

DP. Frolkovi: Application of level set method for groundwater flow with moving boundary, Adv. Wat. Res. 2012

signed distance function

effective flow velocity / groundwater distance velocity

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Free Water Table levelset method

19model domain D (const.)phreatic surface represented by a levelset function

partially saturated zone (not solved here)

fully saturated zone (Darcys law)

groundwater table (moving boundary)(t)(t)D\(t)

DP. Frolkovi: Application of level set method for groundwater flow with moving boundary, Adv. Wat. Res. 2012

signed distance function

effective flow velocity / groundwater distance velocity

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Initial & Boundary Conditions

Nc=1(saturated brine)recharge 2.0 0.1 mm/year, c=0 / seepageinitial condition: water table 14,000 years agosource: Corbet &Knupp 199620

closed boundaries

salt concentration

df++ 2016 Simulationsdensity-driven flow, free water tablegrid level 1 (217 000 prisms) and level 2 (900 000 prisms)21velocity

water table

df++ 2016

Current work:new BMWi-funded project GRUSS (April 2016)improve robustness of solvers (convergence, timesteps)implement volume of fluid (VOF) method to speed-up free surface handling

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Summary of Issues / Path Forward23

Issues Encountered24

Schedule25SECOFL3D data provided by SNLGRS begins building d3f modelSNL begins building PFLOTRAN modelSNL consults

GRS builds d3f model equivalent to Corbet (2000)SNL builds PFLOTRAN equivalent to Corbet (2000)GRS includes density-driven flow

SNL includes density-driven flow to PFLOTRANIncluding new features / dataUpdate boundary conditionsUpdate hydrological implementation and conceptual modelInclude geochemical tracers

Year 1Year 2Year n