Quantifying total iron in brine is critical in order to mitigate its unfavorable effects. An API-sponsored work group has developed a robust field method for determining the levels of iron contamination in all oilfield completion brine, including zinc-based brine. This colorimetric, semi-quantitative method is based on chemistry involving acidification, peroxide oxidation, and thiocyanate complex formation. The iron content is quantified by comparing the intensity of the resulting colored complexes to standards. Using newly-developed, commercially available vacuampoule test kits (Figure 1), this assay is quick and particularly user-friendly, and it is easily implemented in the field. It is anticipated that this method will be incorporated into the API Recommended Practice 13J, Testing of Heavy Brine.
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