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Inhibitor Squeeze Design

Inhibitor Squeeze Design. Effects of divalent and trivalent metal ions (Ca 2+ , Mg 2+ , Fe 2+ , Al 3+ ) on inhibitor return and inhibitor foam squeeze. Outline of Presentation. Overview of inhibitor squeeze chemistry and modeling Effects of Al 3+ , Mg 2+ in overflush on inhibitor return

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Inhibitor Squeeze Design

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  1. Inhibitor Squeeze Design Effects of divalent and trivalent metal ions (Ca2+, Mg2+, Fe2+, Al3+) on inhibitor return and inhibitor foam squeeze

  2. Outline of Presentation • Overview of inhibitor squeeze chemistry and modeling • Effects of Al3+, Mg2+ in overflush on inhibitor return • Effects of Ca2+ in pill and overflush • Effects of Fe2+ in overflush • Preliminary study of inhibitor foam injection

  3. x + y =50 x y Scale Inhibitors Tested Polyacrylate (phosphinopolycarboxylic acid) NTMP DTPMP BHPMP

  4. Back pressure control valve Overflush Pill Column Pump In line pH meter Inh Overflush CO2 and calcite sat. brinereservoir Apparatus and Approach • To simulate linear and radial flow using a series of different diameter packed columns at 75 - 500 psi. • Solid: Ground Frio sandstone, A. E. Guerra core, chalk and calcite. • Inhibitor: NTMP, BHPMP, DTPMP, PAA. • 0.16 pore volume inhibitor, 0.79 pore volume overflush solution was injected. • A calcite saturated synthetic brine was flowed from opposite direction to simulate flow back. • Completely enclosed system to retain inhibitor and carbonate within core apparatus. • Long term inhibitor return, 200-1000 pore volumes, was monitored. 1 pore volume = 1 pill volume+1 overflush volume • Excellent Phn mass balance and reproducibility.

  5. Testing Parameters Return brine: 1000 mg/L Ca, 915 mg/L alkalinity, 1 atm PCO2, pH 5.6

  6. Testing Parameters Return brine: 1000 mg/L Ca, 915 mg/L alkalinity, 1 atm PCO2, pH 5.6

  7. Rock/Core Pill Pill Vol. (Pill + Over flush) Vol. Pill injection (Inhibitor type, concentration, neutralization, and volume) Peak Rock/Core I ? Inh. Conc. II ? III ? Return Flow Volume Squeeze Simulation T, P, Ca, pH, TDS Conversion: 1 Pore Volume = Pill Vol. + Overflush Vol.

  8. 1 4 Ca2+ 3 6 Ca2+ 2 Ca2+ 5 Proposed Inhibitor Retention Mechanism Calcite, surface pH ~9 Cr. Ca-Phn Phase, III Hi. Sol. Ca-Phn Phase, II Am. Sol. Ca-Phn Phase, I pH 4 - 8 Phn chemisorbed at calcite surface to form a low solubility crystalline salt. Further calcite dissolution is inhibited, thus, the pH of the bulk solution is lower than that of the surface boundary. High solubility Ca-Phn phases are formed in bulk solution phase at lower pH. Three Ca-Phn solubility limits are used to model the inhibitor return. The distribution of three Ca-Phn solid phases depends on pill, overflush and formation characteristics.

  9. I II III I II III I II III I II III Comparison of Inhibitor Return • Immediately return – amorphous inhibitor salt. • Medium solubility inhibitor salt. • Thermodynamically most stable inhibitor salt.

  10. Inhibitor Mass Distribution I: Inh return within 3 pore volume. II: Inh return at > 1 mg/L conc. III: Inh return at < 1 mg/L conc.

  11. NTMP Pill Concentrations

  12. Effect of Pill Acidity 4% NTMP Pill

  13. Comparison of Inh. Distribution

  14. DTPMP Return from Different Core Chalk A.E. Guerra Frio Sandstone

  15. Squeeze Life Prediction by SqueezeSoftPitzer V.2.0

  16. NTMP DTPMP BHPMP PPCA Comparison of Inhibitors Pill: 4% acidic inhibitor pH 5.5, 1000 mg/L Ca, 60,000 mg/L TDS, 158 F

  17. Projected Squeeze Life Assume 100 bbl 4% inhibitor, 500 bbl overflush, and 600 BPD water

  18. SqueezeSoftPitzer Prediction Smith Well: 390 bbl 1.55% acidic NTMP, 480 mg/L Ca, 2300 BPD water, 160 F

  19. Inhibitor Selection 182 bbl 3% Acidic Inhibitor, 800 bbl overflush, 2,300 BWPD

  20. Inhibitor Selection 182 bbl 3% Acidic Inhibitor, 800 bbl overflush, 2300 BWPD

  21. Effects of Mg2+, Al3+, Fe2+, Ca2+ in Overflush and Pill

  22. Effects of Mg2+ First 10 PV return Long term Inh Return Mg/DTPMP = 0.6-1.6 Solid Phase Mg and DTPMP conc.

  23. Effect of Al3+ First 10 PV return Long term Inh Return Al ppt as Al(OH)3 Solid Phase Al/DTPMP conc.

  24. Effect of Fe2+ First 10 PV return Long term Inh Return

  25. Flow back of Fe2+/DTPMP Fe/DTPMP = 5 → 1 Fe/DTPMP = 37 → 4 → 1 Fe/DTPMP = 1 → 0.2

  26. Fe/DTPMP = 4 Fe/DTPMP = 5 Solid Phase DTPMP, Fe Distribution After Pill & Overflush Injection After Flow back Injection Fluid: 0.07 M DTPMP 0.1 M Fe 0.054 M DTPMP 0.35 M Fe

  27. Phosphonate Mass Distribution I: Inh return within 3 pore volume. II: Inh return at > 1 mg/L conc. III: Inh return at < 1 mg/L conc.

  28. Effect of Ca2+ Initial Phn. Return Long term Phn. Return

  29. Effect of Ca2+ Initial Ca Return Solid Phase Phn. Distribution

  30. Phosphonate Mass Distribution I: Inh return within 3 pore volume. II: Inh return at > 1 mg/L conc. III: Inh return at < 1 mg/L conc.

  31. Na+ Preliminary Study of Foam Technology in Squeeze Design • To improve sweep efficiency • Aresol MA-80-I: High salt tolerance; previously used in groundwater remediation of chlorinated solvents. • 4% DTPMP in 4% Aresol MA-80-I, 1 M NaCl foam with N2 • Calcite, AEG Column MA-80-I – Sodium dihexyl sulfosunccinate (C16H29O7NaS)

  32. Fe2+, Ca2+ Calcite, surface pH ~9 Cr. Ca-Phn Phase, III Hi. Sol. Ca-Phn Phase, II Am. Sol. Ca-Phn Phase, I Ca2+, H+ Conclusions • Ca and Fe in pill and/or overflush solution significantly increased phosphonate retention. • Mg and Al have little effect on phosphonate retention. • High Fe concentration may cause the phosphonate return concentration to be too low.

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