仕上げ流体としての高温•高比重ブラインの腐食性

抄録

In recent years, solid-free, hight-density brines such as CaBr₂-CaCl₂ or NaBr-NaCl conc. solution, became to be used as completion fluid.
Generally, the advantages using the brines are recognized, i.e, they are chemically stable, and their corrosivity are not high. However, as is usual at pure system, it was concerned about that the circumstanes should change if some contaminant come into those brines, owing to lack of their buffer action.
Several laboratory corrosion tests were carried out in those brines using L-80 test coupons.
In case of oxidizing agent coexisted, the corrosivity of the brines increased drastically. For example, 1% of NaClO3 added into NaBr-NaCl brine, pushed up the corrosion rate more over 80 times as compared with solution of, 1% NaClO₃ only. Organic and inorganic inhibitors were tried to control the corrosion, but the performance of both inhibitors were unsatisfactory in the very severe conditions. This phenomenon is considered to be induced from hydration of high concentrated electrolyte, which restricts free water molecules.
The interpretation was supported by analytical research of ¹H-NMR measurements of thebrines.