The objective of this study is to evaluate the corrosion protection of carbon steel by sodium nitrite (NaNO2) in simulated oilfield produced water, which is a laboratory saline solution, representing a real oilfield produced water from the oil & gas treatment plant. This saline solution contains 20% salt.of 20 wt.% of NaCl, 800 mg/L of MgCl2, 600 mg/L of CaCl2, and 1500 mg/L of Na2SO4, the pH of which was adjusted to 7.5-8.0 with the addition of sodium hydroxide (NaOH) to represent a water produced from an oil and gas treatment system. The laboratory tests used in this investigation were mass loss and electrochemical polarization polarization employing, in each assay, the standardized saline solution with and without additions of 100 mg/L, 250 mg/L, and 500 mg/L of sodium nitrite (NaNO2) as a corrosion inhibitor. The average corrosion rates of carbon steel coupons obtained in the mass loss tests when adding 250 and 500 mg/L of NaNO2 were 0.009 mm/y and 0.004 mm/y, respectively. Such results can be considered excellent for waters with high salinity. Electrochemical polarization curves demonstrate that increasing nitrite concentrations in the simulated oilfield produced water reduce the corrosion current and significantly increase the corrosion inhibition efficiency.
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