Corrosive Environment

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Corrosion is the deterioration of a material due to interaction with its environment and can cause unforeseeable and irreparable fractures in Oil & Gas wells. Selection of the appropriate OCTG material for a given application is driven by 2 main properties: strength and resistance to corrosion. 
 
 
 
 
While corrosion in oil & gas we​lls is a complex phenomenon influenced by many parameters, the primary corrosion failure modes to be taken into account are:
  1. ​Metal-loss corrosion mostly related to presence of CO2 and water :

    1. General corrosion,
    2. Localized corrosion such as pitting and crevice
  2. Environmental cracking mostly related presence of Hydrogen sulfide (H2S):
    1. Sulphide Stress Cracking (SSC),
    2. Stress Corrosion Cracking (SCC) when CO2 is also present
​​​As Corrosion has its unique challenges, it requires experienced specialists to provide guidance on the solutions available. 

Challenges​

The main challenges when dealing with corrosive wells are:

  • Selecting the right material to mitigate corrosion issues while remaining economically viable and while keeping exceptional mechanical performance.

Indeed corrosion of a pipe in oil & gas wells depends on many parameters such as well conditions (pressure, temperature), gas composition (pCO2, pH2S) and water composition. Vallourec can help you selecting the most appropriate material with material recommendations supported by our long dated expertise in metallurgy and corrosion, an extensive database of corrosion test results (SSC, SCC, pitting, crevice) and extensive field records.

  • Ensuring well integrity with strong quality assurance from product manufacturing to installation.

With a strong know-how in steel process, in-house testing facility, recommendations on supply, handling, storage and running of your corrosion resistant material, Vallourec is your supplier of choice for these demanding corrosive applic​ations.

Solutions

To be able to provide answers to these challenges constant development of products, testing, manufacturing and services has been ongoing within Vallourec including:

  • In CO2 environment (pCO2 > 2 psi), Carbon steel suffers Metal-Loss corrosion and 13%Cr & Super 13%Cr are the most cost effective solution to cope with CO2 corrosion.
  • When tubings and casings are exposed to H2S (pH2S > 0.05psi) in addition to the CO2 (pCO2 < 2psi), Sour Service grades must be used.  These can be either API or proprietary grades (VM80SS to VM125SS), tested according method A of NACE TM0177 or Method D (DCB test) for (VM95SS-D; VM110SS-D) and can be combined with High Collapse properties (VM80HCSS to VM125H​CSS).
  • With high concentration of H2S (pH2S > 1.5psi), in addition to high concentration of CO2 (pCO2 > 2psi), corrosion, resistant alloy (CRA) made of high-chromium and high-nickel alloy steel such as VM 22, VM ​25S, VM 28, VM 825, V​M G3, VM 50 must be used.
  • Integrated testing capacities to perform reliable tests in your most severe conditions: HP/HT​ conditions; Low T°C; Higher Partial Pressure of CO2 or H2S than NACE solutions; Tests at Actual Yield Strength and not only at SMYS.
  • Integrated accessories manufacturing to ensure an homogeneous procurement (pipes & accessories) following same quality plan, same material and a logistics coordination.
  • Manufacturing of challenging products such as thick tubes in CRA or Integral connections in Sour Service with stress relief & deformation rate of the material controlled.
  • Thread compound qualification is available with all Corrosive Resistant materials.
  • Well design analysis combined with Material selection recommendations.
  • VAM® lic​ensee netw​ork clo​se to customers' operations​.
  • Worldwide network of VAM® Field Service making sure pipes are run properly.