1 / 35

Inverse Mass-Balance Modeling versus “Forward Modeling”

2% CO 2. atm CO 2. Inverse Mass-Balance Modeling versus “Forward Modeling”. How much calcite precipitates?. Forward Approach What is the strategy? What data do you need? What assumptions do you need to make?. Limestone. Inverse Approach?. Final Solution. Initial Solution.

sorena
Download Presentation

Inverse Mass-Balance Modeling versus “Forward Modeling”

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 2% CO2 atm CO2 Inverse Mass-Balance Modelingversus “Forward Modeling” How much calcite precipitates? Forward Approach What is the strategy? What data do you need? What assumptions do you need to make? Limestone Inverse Approach?

  2. Final Solution Initial Solution Solid to Solution (dissolution, exchange) Solution to Solid (precipitation, exchange) Need to Know Initial Solution Final Solution Reacting Phases gases, water

  3. Well 1 Well 2 Inverse modeling is applicable when: Waters are evolutionary!

  4. No mixing. (initial water may be formed by mixing two waters) Well 1 Well 2 OK OK No

  5. high school algebra always looking for n equations with n unknowns 2x + 3y -2z = 3 x + 3y - z = 2 3x + 2y + 5z = 7 Variables = Constraints (elements, electrons, isotopes) Equations are the mineral reactions. How we do the mass balance (the very short version)

  6. Initial Solution  Final Solution  (mg/kg)  (mg/kg) Na 12 4 Ca 49 11 Mg 3 3 Cl 12 17 HCO3- 2% CO2 104 15 atm CO2 How much calcite precipitates?

  7. Sierra Nevada Spring CompositionsGarrels and Mackenzie (1967) .016 "Halite" NaCl .015 "Gypsum" CaSO4 .427 CO2 gas CO2 .115 Calcite CaCO3 0 Silica SiO2 .014 Biotite KMg3AlSi3O10(OH)2 .175 Plagioclase An38 Na0.62Ca0.38Al1.38Si2.62 -.033 Kaolinite Al2Si2O5(OH)4 -.081 Ca-Montmorillonite Ca0.17Al2.33Si3.67O10(OH)2 mass transfers (mmol/kg water)

  8. Sierra Nevada Spring CompositionsGarrels and Mackenzie (1967) Ephemeral Spring Perennial Spring

  9. SOLUTION 1 Ephemeral Springs temp 25 pH 6.2 pe 4 redox pe units mmol/kgw density 1 Ca 0.078 Cl 0.014 K 0.028 Mg 0.029 Na 0.134 S(6) 0.01 Si 0.273 Alkalinity 0.328 -water 1 # kg SOLUTION 2 Perennial Springs temp 25 pH 6.8 pe 4 redox pe units mmol/kgw density 1 Ca 0.41 Cl 0.03 K 0.04 Mg 0.071 Na 0.259 S(6) 0.025 Si 0.41 Alkalinity 0.895 -water 1 # kg

  10. Always as dissolution Thermo data

  11. Plagioclase (An38) Na0.62Ca0.38Al1.38Si2.62O8 + 5.52H+ + 2.48H2O = 1.38Al+3 + 0.38Ca+2 + 2.62H4SiO4 + 0.62Na+ Biotite ? KMg3AlSi3O10(OH)2

  12. #1 Phase mole transfers: Minimum Maximum Halite 1.600e-005 1.490e-005 1.710e-005 NaCl Gypsum 1.500e-005 1.412e-005 1.587e-005 CaSO4:2H2O Kaolinite -1.295e-004 -1.403e-004 -1.193e-004 Al2Si2O5(OH)4 CO2(g) 3.088e-004 2.527e-004 3.702e-004 CO2 Calcite 1.079e-004 8.680e-005 1.144e-004 CaCO3 Chalcedony -1.108e-004 -1.473e-004 -7.528e-005 SiO2 Biotite 1.370e-005 1.317e-005 1.370e-005 KMg3AlSi3O10(OH)2 Plag(An38) 1.777e-004 1.629e-004 1.934e-004 Na0.62Ca0.38Al1.38Si2.62O8 #2 Phase mole transfers: Minimum Maximum Halite 1.600e-005 1.490e-005 1.710e-005 NaCl Gypsum 1.500e-005 1.412e-005 1.587e-005 CaSO4:2H2O Kaolinite -3.316e-005 -5.381e-005 -1.223e-005 Al2Si2O5(OH)4 Ca-Montmorillon -8.269e-005 -1.099e-004 -5.618e-005 Ca0.165Al2.33Si3.67O10(OH)2 CO2(g) 2.951e-004 2.392e-004 3.563e-004 CO2 Calcite 1.216e-004 1.007e-004 1.279e-004 CaCO3 Biotite 1.370e-005 1.317e-005 1.370e-005 KMg3AlSi3O10(OH)2 Plag(An38) 1.777e-004 1.629e-004 1.934e-004 Na0.62Ca0.38Al1.38Si2.62O8 #3 Phase mole transfers: Minimum Maximum Halite 1.600e-005 1.490e-005 1.710e-005 NaCl Gypsum 1.500e-005 1.412e-005 1.587e-005 CaSO4:2H2O Ca-Montmorillon -1.112e-004 -1.204e-004 -1.024e-004 Ca0.165Al2.33Si3.67O10(OH)2 CO2(g) 2.904e-004 2.358e-004 3.503e-004 CO2 Calcite 1.262e-004 1.067e-004 1.313e-004 CaCO3 Chalcedony 3.814e-005 1.407e-005 6.189e-005 SiO2 Biotite 1.370e-005 1.317e-005 1.370e-005 KMg3AlSi3O10(OH)2 Plag(An38) 1.777e-004 1.629e-004 1.934e-004 Na0.62Ca0.38Al1.38Si2.62O8

  13. SOLOUTION 2 Perennial Spring FINAL Phase SI log IAP log KT Anhydrite -3.99 -8.35 -4.36 CaSO4 Aragonite -1.92 -10.26 -8.34 CaCO3 Calcite -1.78 -10.26 -8.48 CaCO3 Chalcedony 0.16 -3.39 -3.55 SiO2 Chrysotile -10.85 21.35 32.20 Mg3Si2O5(OH)4 CO2(g) -2.05 -20.20 -18.15 CO2 Dolomite -3.99 -21.08 -17.09 CaMg(CO3)2 Gypsum -3.77 -8.35 -4.58 CaSO4:2H2O H2(g) -21.60 -21.60 0.00 H2 H2O(g) -1.51 -0.00 1.51 H2O Halite -9.73 -8.15 1.58 NaCl O2(g) -39.92 43.20 83.12 O2 Quartz 0.59 -3.39 -3.98 SiO2 Sepiolite -7.17 8.59 15.76 Mg2Si3O7.5OH:3H2O Sepiolite(d) -10.07 8.59 18.66 Mg2Si3O7.5OH:3H2O SiO2(a) -0.68 -3.39 -2.71 SiO2 Talc -6.82 14.58 21.40 Mg3Si4O10(OH)2

  14. #1 Phase mole transfers: Minimum Maximum Halite 1.600e-005 1.490e-005 1.710e-005 NaCl Gypsum 1.500e-005 1.412e-005 1.587e-005 CaSO4:2H2O Kaolinite -1.295e-004 -1.403e-004 -1.193e-004 Al2Si2O5(OH)4 CO2(g) 3.088e-004 2.527e-004 3.702e-004 CO2 Calcite 1.079e-004 8.680e-005 1.144e-004 CaCO3 Chalcedony -1.108e-004 -1.473e-004 -7.528e-005 SiO2 Biotite 1.370e-005 1.317e-005 1.370e-005 KMg3AlSi3O10(OH)2 Plag(An38) 1.777e-004 1.629e-004 1.934e-004 Na0.62Ca0.38Al1.38Si2.62O8 #2 Phase mole transfers: Minimum Maximum Halite 1.600e-005 1.490e-005 1.710e-005 NaCl Gypsum 1.500e-005 1.412e-005 1.587e-005 CaSO4:2H2O Kaolinite -3.316e-005 -5.381e-005 -1.223e-005 Al2Si2O5(OH)4 Ca-Montmorillon -8.269e-005 -1.099e-004 -5.618e-005 Ca0.165Al2.33Si3.67O10(OH)2 CO2(g) 2.951e-004 2.392e-004 3.563e-004 CO2 Calcite 1.216e-004 1.007e-004 1.279e-004 CaCO3 Biotite 1.370e-005 1.317e-005 1.370e-005 KMg3AlSi3O10(OH)2 Plag(An38) 1.777e-004 1.629e-004 1.934e-004 Na0.62Ca0.38Al1.38Si2.62O8 #3 Phase mole transfers: Minimum Maximum Halite 1.600e-005 1.490e-005 1.710e-005 NaCl Gypsum 1.500e-005 1.412e-005 1.587e-005 CaSO4:2H2O Ca-Montmorillon -1.112e-004 -1.204e-004 -1.024e-004 Ca0.165Al2.33Si3.67O10(OH)2 CO2(g) 2.904e-004 2.358e-004 3.503e-004 CO2 Calcite 1.262e-004 1.067e-004 1.313e-004 CaCO3 Chalcedony 3.814e-005 1.407e-005 6.189e-005 SiO2 Biotite 1.370e-005 1.317e-005 1.370e-005 KMg3AlSi3O10(OH)2 Plag(An38) 1.777e-004 1.629e-004 1.934e-004 Na0.62Ca0.38Al1.38Si2.62O8

  15. "Halite" NaCl "Gypsum" CaSO4 CO2 gas CO2 Calcite CaCO3 Silica SiO2 Biotite KMg3AlSi3O10(OH)2 Plagioclase An38 Na0.62Ca0.38Al1.38Si2.62 Kaolinite Al2Si2O5(OH)4 Ca-Montmorillonite Ca0.17Al2.33Si3.67O10(OH)2 albite NaAlSi3O8 anorthite CaAl2Si2O8 This would allow variable plagioclase composition, but needs to be near An25 biotite dissolution vermiculite precipitation This would allow for K+ release by Fe2+ oxidation in the biotite Evaporative Concentration? Deep Brine?

  16. Stop while you can!

  17. How do you determine the mineralogy? Thin Section and use an ion probe or a SEM with EDX Mineralogy and composition of specific minerals. Poor job of fine grained secondary phases such as clays and oxy-hydroxides X-ray diffraction Gives mineralogy, including fine grained phases and clays. Does not give the specific mineral compositions. Geologic/Hydrologic Information A good guess.

  18. Snowmelt Ephemeral Spring Perennial Spring

  19. 24Sierra Nevada Spring CompositionsGarrels and Mackenzie (1967) "Halite" NaCl "Gypsum" CaSO4 CO2 gas CO2 Calcite CaCO3 Silica SiO2 Biotite KMg3AlSi3O10(OH)2 Plagioclase An38 Na0.62Ca0.38Al1.38Si2.62 Kaolinite Al2Si2O5(OH)4 Ca-Montmorillonite Ca0.17Al2.33Si3.67O10(OH)2 Problem: Can the Ephemeral Springs be the result of weathering in the soil zone?

  20. SOLUTION 1 Ephemeral Springs temp 25 pH 6.2 pe 4 redox pe units mmol/kgw density 1 Ca 0.078 Cl 0.014 K 0.028 Mg 0.029 Na 0.134 S(6) 0.01 Si 0.273 Alkalinity 0.328 -water 1 # kgSOLUTION 3 Precipitation temp 25 pH 5.8 pe 4 redox pe units umol/l density 1 Na 0.11 Ca 0.068 Mg 0.022 K 0.02 S(6) 0.01 Cl 0.013 Si 0.27 Alkalinity 0.314 -water 1 # kg INVERSE_MODELING 1 -solutions 3 1 -uncertainty 0.05 0.05 -phases Kaolinite Ca-Montmorillonite CO2(g) Plag(An38) SiO2(a) Gypsum K-feldspar Biotite -tolerance 1e-010 -mineral_water truePHASESPlag(An38) Na0.62Ca0.38Al1.38Si2.62O8 + 5.52H+ + 2.48H2O = 1.38Al+3 + 0.38Ca+2 + 2.62H4SiO4 + 0.62Na+ log_k 0Biotite KMg3AlSi3O10(OH)2 + 6H+ + 4H2O = Al(OH)4- + 3H4SiO4 + K+ + 3Mg+2log_k 0END No halite or calcite. Add K-feldspar.

  21. Phase mole transfers: Minimum Maximum Kaolinite -4.796e-005 0.000e+000 0.000e+000 Al2Si2O5(OH)4 Ca-Montmorillon -9.511e-005 0.000e+000 0.000e+000 Ca0.165Al2.33Si3.67O10(OH)2 CO2(g) 7.739e-004 0.000e+000 0.000e+000 CO2 Plag(An38) 2.098e-004 0.000e+000 0.000e+000 Na0.62Ca0.38Al1.38Si2.62O8 SiO2(a) 8.404e-005 0.000e+000 0.000e+000 SiO2 Gypsum 9.990e-006 0.000e+000 0.000e+000 CaSO4:2H2O K-feldspar 1.832e-005 0.000e+000 0.000e+000 KAlSi3O8 Biotite 9.659e-006 0.000e+000 0.000e+000 KMg3AlSi3O10(OH)2 No halite or calcite. How would you get these in the soil? Add K-feldspar. That makes sense. But….Gypsum? There is something we are missing with SO4

  22. Isotopes -isotopes 13C 34S PHREEQC treats each isotope as a separate component. Calcite is no longer CaCO3 it is now: CaC12.999C13.001O3 PHREEQC does NOT handle fractionation processes. NETPATH handles fractionations, but does not allow uncertainty in the concentrations measurements.

  23. Mixing Use -Mix to make a starting solution, and use this as the initial solution.

  24. Olivine MgSiO4 FeSiO4 Mg-calcite MgCO3 CaCO3 solid solutions - use a mixture of the end members individually -balances used to force balancing of an element not in the solid phases For example, Cl- to quantify evaporation in a soil. Evaporation - include H2O as a heterogeneous phase “precipitation” of H2O = evaporation

  25. No Way

  26. Suggestions: Try to only change one thing at a time. The solid phases are important. It helps to look at the solids! Many minerals are messy, but the variations in composition can be important. The model results will only be as reliable as your understanding of the hydrochemical system.

More Related