ScaleSoftPitzer Overview and Use

1. ScaleSoftPitzer Overview and Use • Explain Input Cells • Calculate inhibitor needed with and without MeOH • Illustrate the GoalSeek-type feature: • A. What P-CO2 would make the downhole SI = 0.00 • B. What seawater SO4 level would make the Inh Conc. • equal to 1) zero, 2) a small value (e.g., 0.01 mg/l) • Use of SSP SI values to calculate precipitation • and dissolution in flooding

4. CaCO3 Fe(OH)2 MgSiO3 Na2SiO3 (H2CO3 + HAc + H2S + HCl)aq H2CO3 + HAc + H2S + H2O + NaCl HCO3- Ac- HS- OH- SiO2 CO32- S2- -H+ Weak-acid buffer solutions. Alk  [HCO3-] + 2[CO32-] + [Ac-] + [HS-] +2[S2-] + [OH-] - [H+] in units of (eq./L)  [HCO3-] + [Ac-]  [HCO3-] • 1. If you are given HCO3- as mg/l HCO3,then enter this number as Alkalinity in Cell C21; • 2. If you are given Alkalinity as mg/l HCO3, then enter this number as Alkalinity in Cell C21; • 3. If you are given Alkalinity as mg/l of CaCO3, then multiply this value by 1.22 and enter the product as Alkalinity in Cell C21; • 4. If you are given both mg/l HCO3 and mg/l CO32-, then multiply mg/l CO3 by 2.03 and add to mg/l HCO3 and enter the sum as Alkalinity in Cell C21; 5. If you are given a value for phenolphthalein Alkalinity as mg/l CaCO3 in addition to bicarbonate alkalinity as mg/l CaCO3, then add these together and multiply by 1.22 and enter the result as Alkalinity in Cell C21. Alkalinity in oilfield brines

5. The two pH options: I. (0, no), do not use measured pH; and II. (1, yes), use the measured pH

6. H2S gas and solution

7. Carboxylic Acids and Total Dissolved Solids (TDS)

8. Effect of pressure and gas, oil, and water volumes on gas composition In the water in each case: [HCO3-] =305 mg/L =0.005 eq/L (M) STP conditions Pressure = 1 atm Volume = 200,000 ft3 yCO2 = 0.01 Pressure at some point down the well: Pressure = 400 atm Volume = 109 ft3 yCO2 = 0.0011 Hy=“hydrocarbon” in g/o/w phases. Pressure at bubble point = 513 atm; Volume of gas = 0.0 CO2 Hy CO2 Hy 100 B of Oil 100 B of Oil 100 B of Oil CO2 Hy CO2 Hy CO2 Hy CO2 Hy CO2 Hy CO2 Hy 1000 B of W 1000 B of W 1000 B of W CO2,w = 0.00028 M pH = 7.25 CO2,w = 0.0120 M pH = 5.76 CO2,w = 0.0123 M pH = 5.62

9. Total Dissolved Solids (TDS) and Density

10. Impact of hydrate inhibitors on SI values; present status

11. Protection time, selection of scale inhibitor, and display activity coefficients

12. T, and P values for mixed brines

14. What CO2% would make the SI(calite) equal to zero at well bottom? 1 2 3

16. What seawater SO4 would be needed so that very little (0.01 mg/l) Inhibitor would be needed? A: 24.51mg/L SO4 1 2 3

18. What sulfate would require zero inhibitor? A: 19.12 mg/L

19. Use of ScaleSoftPitzer to calculate deposition, or precipitation, in a reservoir or core material during long term flow.

20. Approach

21. Summary of Approach

22. Kinetics and Mass Transport

23. Relationship of pressure change to flow rate using Darcy’s law

24. Darcy’s law

25. Customary Units

26. re,Pe r,P b(m) rw,Pw Darcy’s Law in Radial Flow

27. Pressure drop vs. radius

28. Calcite precipitation – No gas phase

29. Calcite precipitation – No gas phase

30. Calcite precipitation – with gas phase

31. Barite precipitation

32. Combine SI equations with Darcy’s equation

33. Example

34. Examples

35. List of Key Equations

36. List of key equations

37. b Parameter

38. ScaleSoftPitzer

39. Range of hydraulic Conductivity and Permeability From: R. Allen Freeze and John A. Cherry, “Groundwater,” Prentice Hall, 1979

40. Typical hydraulic Conductivity and Permeability From Jacob Bear’s text on hydrology, 1968.

41. Permeability vs. Porosity

42. Permeability vs. Porosity

43. Permeability vs. Porosity

44. Calculator for flow in radial coordinates