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Autoclaves Approximating test vessel compositions defined in NACE/ISO corrosion testing standards AJ Gerbino OL OLI Simulati ation on Conf nfer eren ence ce 2016 Conference organization by Topics NACE Standards general

  1. Autoclaves Approximating test vessel compositions defined in NACE/ISO corrosion testing standards AJ Gerbino OL OLI Simulati ation on Conf nfer eren ence ce 2016 Conference organization by

  2. Topics • NACE Standards – general overview • Read up on standards to see what clients were preparing in lab • Significant discretion in formulating experiment • Algebraic method to calculate H 2 S and CO 2 loading • Fixed application range • Software approach to calculate H 2 S and CO 2 loading • Reduce or eliminate limits to gas loading • Address flexibility limits to accommodate experiments

  3. • TM0185 - • ANSI/NACE TM0284 - • NACE TM0296 - • NACE TM0198 - • ANSI/NACE TM0177 - • ANSI/NACE MR0175/ISO15156-2 - ANSI/NACE/ISO test methods Highlights of each method presented

  4. TM0185 - Evalu luation of in internal l pla lastic ic coatin ings for corrosion control of tubula lar goods by y autoclave testin ing • No autoclave specifications • Test T/P left to the investigator • At least 25% oil, water, and gas in vessel • Oil is 50/50 toluene/kerosene • Water is fresh or brine • Gas is single or multicomponent • 3-page document, few details, no apparatus image

  5. TM0284 - Evalu luation of pip ipelin line and pressure vessel l steels ls for resis istance to H-in induced crackin ing • Not an Autoclave test – ambient P and T • Four water options • A: NaCl + HAc + H2S bubbling – 2.7 to 3.2pH • B: Synthetic Seawater +H2S bubbling – 4.8 to 5.4pH • C: NaCl + NaAc +H2S/CO2 bubbling – target pH • D: TM0177 solution B • Minimum liquid volume per sample area • H 2 S or H 2 S/CO 2 bubbled continuously to maintain constant PP • 27-page document, very detailed regarding sample and analysis

  6. TM0296 - Evalu luatin ing Ela lastomeric materia ials in in sour liq liquid id envir ironments • Fixed volume ratios • Water=5% • Oil=60% • Sample <4% • Gas = balance • Water composition not defined • Three HC compositions (alkanes, kerosene) • Two Gas mixtures (H2S up to 20%) • Test T 100-175C, Test P 6.75MPa • O2 purging (all standards describe this) • Autoclave required

  7. TM0198 – Slo Slow str train in rate tes est method for r screening CRA for r str tress corr rrosion cracking in in so sour oilf ilfield se serv rvices • No specified water composition. • Water is 80% of volume • Gas mixture of CO 2 ,H 2 S, N 2 , Ar, or CH 4 • No test T and P defined

  8. TM0177- Lab testin ing for resis istance to SSC and SCC in in H 2 S envir ironments • Four test solutions • Test gas usually mixture; H2S, CO2, Ar, N2 • Test gas replenished to maintain P H2S • Continuous gas bubbling an option at test T/P • <75% liquid volume

  9. MR0175 - Petrole leum and materia ial gas in industries - materials ls for use in in H2S-containing envir ironments • Initial publication 1975 • Provides estimates for determining P H2S and pH Annex D – determining pH Annex C – determining P H2S P T ,MPa Y H2S ,ppmV

  10. Summary ry of f method limitations, uncertainties • Major limitations – • Setting target properties at elevated T and P when loading is performed at ambient conditions • Minor limitations – • Liquids loading effects on gas partitioning • Formulated water properties • Remaining headspace composition following N2 purging

  11. J.L. Crolet and M.R. Bonis. 2000. How to pressurize Autoclaves for Corrosion testing under CO 2 and H 2 S Pressure . Corrosion 56(2) pp. 167-182 Alg lgebraic method to lo load a sealed autoclave Approach for resolving the major limitation of achieving target H2S and CO2 at HPHT

  12. Crolet/Bonis method • Defines S H2S , S CO2 (mmol/L-bar) • a “Physical Solubility” term • Units of molar gas concentration in water per partial pressure • Also referred to as an inverse Henry’s constant • Defines a similar term S G for each component • Gas concentration in gas (mmol/L gas -bar) • Computes total moles H 2 S/CO 2 in vapor and water • Includes an adjustment for Gas-Liquid loading ratio

  13. S H2S , S CO2 (m (mmol/l-bar) physical solu lubility coefficient S values are obtained from linear fit of solubility data S H2S at 38C S CO2 @ 100C 2000 250 y = 68.2*PH2S (mmol/L-bar) y = 10.5*PCO2 (mmol/L-bar) 1600 200 CO2, mmol/L H2S, mmol/l 1200 150 800 100 400 50 Ref #1 Ref #2 0 0 0 10 20 30 0 5 10 15 20 25 PH2S, bar PCO2, bar

  14. T-dependent S S H2S , , S CO2 , , and S G AQ Fwk MSE Fwk 100.0 100 S H2S S H2S S CO2 S CO2 S G S G S H2S (OLI) S CO2 (OLI) S H2S (OLI) S G (=1000/RT) S CO2 (OLI) 0.0 0 0 200 0 200 S_H2S (fug) S CO2 and S H2S units are mmol/L-bar S G units are mmol/L(vapor)-bar = same for all gases

  15. H 2 S/CO 2 Loading using Crolet and Bonis’ algebraic method “Gas moles moles Total moles “Physical Gas-Liquid = = solubility” H2S in H2S in solubility” volume H2S in based on gas Liquid vapor (mol/l-bar) ratio autoclave law (1/RT) Example application, H 2 S loading in 1L autoclave vessel with different GLR Case T S H2S S G P H2S V L V G GLR M H2S,L M H2S,V X H2S * C mmol/l-bar bar L L mmoles mmoles mmol/L 1 30 75 39.7 0.01 0.5 0.5 1.0 0.4 0.2 0.6 2 60 35 36.1 0.003 0.8 0.2 0.3 0.1 0.0 0.1 3 100 21 31.4 0.04 0.3 0.7 2.3 0.3 0.9 1.1 4 150 18 28.4 0.7 0.2 0.8 4.0 2.5 15.9 18.4 * Authors define X H2S as dissolved H 2 S in Similar equation for CO2 loading water

  16. Algebraic method transitioning to OLI calculations • Method for P CO2 and P H2S . Carrier gases are omitted. • S H2S , S CO2 values based on linear portion of solubility curve. Solubility is non-linear at higher pressures • Method excludes H 2 S/CO 2 partitioning to oil phase • Any aqueous reactions are ignored 3000 H2S (mmol/L) = 40*PH2S 2500 2000 H2S, mM 1500 93C data 1000 500 Ref #3 0 0 20 40 60 80 100 PH2S (bar)

  17. OLI I Studio and Flo lowsheet ESP on Standard methods Incorporating Mass balance & phase-partitioning to fill the void from the algebraic method limit

  18. Specifications/Requirements • Tool must enable • Water, oil and gas formulations • Water and oil loading volumes • Sample loading volume • Tool must calculate • target pH before loading or after H 2 S bubbling • P N2 in headspace following purge step • target P H2S , P CO2 , at test • target C H2S , C CO2 at test (client specific) • Target P H2S , P CO2 after test depressurizing (client specific) • P H2S,ambient and P CO2,ambient to achieve target P H2S and P CO2 at test

  19. Complications • Reagent and Test procedure is multi-step • Some steps are cyclical, requiring iterations • Some steps are not easy to create in a simulator tool

  20. Option #1 - Single-Point Autoclave • Accomplishes • Final P CO2 , P H2S , loading • Does not accomplish • H 2 S and CO 2 loading pressure • Individual phase volume • Individual phase composition • Sample volume • OLI Studio Analyzer. Single Point Calculation type

  21. OLI Studio – Basic Autoclave calc.

  22. Option #2 Flo lowsheet TMO198 Stress testing in CaCl2 brine • Configuration Specifications • Four Flow controllers - Four valves V T =0.5L • Six mixers (7 th for measurement only) V L =0.4L CaCl2 • Three pressure controllers V specimin =not included P H2S , depressurized =15% • Accomplishes P CO2 , depressurized =9% • P H2S and P CO2 loading pressures P test =2000psia • individual phase compositions T test =149 • more complicated software is required View Software

  23. Flowsheet ESP approach

  24. Option #3 - OLI I Studio Mix ixers in in seri ries • Configuration • Six mixers, one for each autoclave charging and heating step • Flowsheet pressure controllers are replaced by new isochoric calculation • Manual iterations to converge case • Autoclave Step 6 (mixer) is calculated • H 2 S, CO 2 , N 2 inflows (multipliers) in Steps 3, 4, and 5 mixers adjusted manually until pp targets in Step 6 are met • Accomplishes • P H2S and P CO2 loading pressures • individual phase compositions • Does not accomplish • The user is the flow controller • Mixer inflows are limited to multipliers, not View Software volume

  25. OLI Studio – Cascading Mixers

  26. Summary ry • NACE documents appear to be more guidelines than specific instructions, and clients have experimental latitude • Apply electrolyte software to address limits to achieving target properties in ANSI/ASTM/NACE methods and user-modified methods • Single-point Autoclave application range is limited • Complete simulation possible using Flowsheet software • Using the mixers in OLI Studio with isochoric calculation expands the OLI Studio range

  27. Acknowledgement Partial list of clients/colleagues that have provided advice, information, or direction on developing a better autoclave simulation application in OLI software • Brent Sherar, Blade Energy • Rudy Hausler, Blade Energy • Tracey Jackson, Baker Hughes • Pilan Esteban, Tubacex • George Winning, Element

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