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Technical Frequently Asked Questions
"Corrosion caused by Inductive currents"
Question:
"Would
one expect corrosion to occure if a metal was inductively heated
while submerged in water? This water could contain dissolved gases
and salts. With induction heating, the induced currents are AC.
This is thus a significantly different problem from that of DC
currents, flowing in a similar geometry, where significant corrosion
would be expected to occur. The water would be produced along with
oil in a producing well. Water could amount to 90% of the flow,
but might typically be 50%. This water often contains dissolved
CO2 (2%, say), and dissolved salts, Na, etc. Temperature, generally
less than 100'C. Pressures, would be generally be less than 2000psi
hydroststic, but could be less than 100 psi in a drawdown situation.
The casing material is J-55, standard oilfield casing."
Answer:
We
do not proclaim ourselves to be experts on corrosion induced by "inductive currents";
however, our experience says that the susceptibility to corrosion,
independent of the environment, will be based on the metal temperature.
Therefore, the higher the metal temperature, below where water
is present as as liquid, the greater corrosion can be expected
to be.
This fact, as in all things related to corrosion, has its caveats, as the above information depends on whether you are describing a closed or open system. In a closed system, dissolved, corrosive gasses such as oxygen and carbon dioxide, cannot dissipate due to reduced solubility at increased temperatures; however, in open systems, dissolved gasses can be reduced. At your stated environmental conditions, I might expect corrosion of J-55 material to be a problem, due primarily to dissolved carbon dioxide.
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