engleski

DETERMINATION OF INORGANIC IONS IN THE OILFIELD WATER BY ION CHROMATOGRAPHY

Large amounts of oilfield water are produced during the production of crude oil and natural gas. This water has to be analyzed to realize the correct geological formation. Cations and anions are the main interest of this analysis and determination of anions are carried out using ion chromatography (IC). Determinations of anions were done in the past by using gravimetric, volumetric and photometric methods. These methods, unfortunately, analyze only one type of ion per operation. Ion chromatography offers an alternative, method to determine mentioned anions in short time and with lower effort. The fastest and the most accurate analysis could be performed if the instrumental parameters are carefully selected. For that case, full optimization process of ion chromatographic system should be done. Retention modeling and Multy Criteria Decision Making (MCDM) technique to select the IC optimum are mostly required. In this work, artificial neural network for modeling of gradient retention is combined with several optimizations objective functions and 4 robustness functions in order to find the most appropriate combination to be applied in IC method development. The used multicriteria were: maximal value of resolution function (objective function), minimal analysis time, maximal retention distance among two nearest neighboring components, and maximal robustness of the used resolution function. Optimal elution method was used and validated for determinations of fluoride, chloride, bromide, nitrate and sulfate in oilfield water analyses.

ion chromatography; oilfield water; multy criteria decision making

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