To ensure the produced oil meets the quality requirements, all chemical agents used in the process of oil production are checked for content of organic chlorine compounds. TatNIPIneft Institute has developed a procedure based on X-ray fluorescence analysis for prompt determination of organochlorine compounds in chemicals’ samples using spectral scanning wavelength-dispersive X-ray fluorescence analyzer, Spectroscan CLSW. The technique allows to measure a mass fraction of organic chlorine compounds in the chemical sample. If the chemical sample (which is an organic-based composition) is a water-based composition, both organic and inorganic chlorine compounds might be present in it. It has been offered to extract organochlorine compounds to isooctane or hexane and to determine the mass fraction of organic chlorine in the extract. The similar approach is used for analysis of hydrochloric acid or HCl-based compositions’ samples. The outcome of the X-ray fluorescence analysis is total content of organic chlorine compounds in the chemical agent sample, including highly volatile forms. Gas chromatography-mass spectrometry method is used to determine the content of organic chlorine in highly volatile organochlorine compounds, as well as the type of these compounds. Shimadzu gas chromatograph/mass spectrometer is used for the purpose. The chromatography-mass spectrometry procedure is detailed in the “Procedure for measurement of mass fraction of volatile organochlorine compounds in chemical agents using gas chromatography method with mass-selective detection”. Combination of two approaches to determine the content of organic chlorine compounds in samples optimizes the costs. In some corrosion inhibitors or bactericides, etc., chlorine compounds are present, which are not classified as organochlorine compounds, but when heated, they are decompounded forming organochlorine compounds. For example, alkyldimethylbenzylammonium chloride when heated is decompounded forming benzyl chloride. To assess chemical agents’ stability to decompounding, a thermal stability test is performed. Chemical agent with the dosage corresponding to the actual chemical concentration in field is added into a synthetic emulsion that was obtained from oil without organochlorine compounds and mineralized water. The emulsion is dehydrated, naphta is distilled form of oil, and the content of organic chlorine in the distilled naphta is determined in accordance with GOST Р 52247-2004, Method В.
Integrated approach to chemical agents control helps to avoid purchase of chemical agents containing organochlorine compounds, thus, ensuring that stock-tank oil quality meets the requirements of regulatory documents.
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8. Patent RU 2 740 991 C1, Method of determining content of organic chlorine in chemical reagents used in oil production, Inventors: Tatyanina O.S., Gubaidulin F.R., Sudykin S.N., Abdrakhmanova L.M.
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