Iron contamination in oilfield brines is typically a result of corrosion processes of iron-containing metallic components and equipment.  Accumulation of insoluble iron salts in a brine completion fluid can result in substantial formation damage and can significantly affect the productivity of an oil well.  Quantifying total iron in brine is critical.

The Colorimetric Method.  The Iron in Brine test method employs the ferric thiocyanate chemistry.  In an acidic solution, hydrogen peroxide oxidizes ferrous iron.  The resulting ferric iron reacts with ammonium thiocyanate forming a red-orange colored thiocyanate complex, in direct proportion to the iron concentration.

    The method reports total iron content in units of mg/L.  By simply dividing the measured mg/L by the density of the brine reported in units of kg/L, the ppm value can be obtained in mg/kg.