Method for testing chelating ability of chelating acid to metal calcium ions

Abstract

The invention provides a method for testing the chelating ability of a chelating acid to metal calcium ions. The method comprises the following steps: taking a chelating acid solution, titrating the chelating acid solution by using a calcium acetate standard solution in the presence of a buffer solution until an end point is reached, calculating the chelating ability of the chelating acid to the calcium ions according to formula (1), and representing the chelating ability by the amount of the sample chelated calcium ions: omega(Ca) = (C1*V1*M) / (m1 / V2*V3), wherein omega(Ca) representing the calcium ion chelating ability, mg / g; C1 representing the concentration of the calcium acetate solution, mol / L; V1 representing the consumption volume of the calcium acetate solution, mL; M representing the molar mass of calcium, g / mol; m1 representing the mass of the sample, g; V2 representing an accurate volume value after 500 mL volumetric flask calibration, mL; and V3 representing an accurate volume value after 100 mL pipet calibration, mL. The determination method has the advantages of simplicity and rapidness in operation, and easiness in promotion and use.

Description

technical field [0001] The invention relates to the field of petrochemical industry, in particular to a method for testing the chelating ability of chelating acid to metal calcium ions. Background technique [0002] Acidizing operation is an important measure to ensure increased production and injection in oilfield development. The main mechanism of sandstone acidification is the reaction of hydrofluoric acid with aluminosilicate and fluoroaluminate, but calcium hydroxide precipitation may be formed during the reaction. Therefore, whether the effective chelation of precipitated ions can be realized is an important index to investigate the performance of chelating acid. [0003] At present, the chelating ability test method commonly used in laboratory experiments is mainly to observe the precipitation by uniformly mixing the acid solution with sodium carbonate and calcium chloride solutions. This process requires repeated addition of sodium hydroxide solution to adjust the p...

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Problems solved by technology

[0003] At present, the chelating ability test method commonly used in laboratory experiments is mainly to observe the precipitation by uniformly mixing acid solution with sodium carbonate and calcium chloride solution. This process requires repeated addition of sodium hydroxide solution to adjust the pH value of the mixture, and the test operation is difficult. It is difficult to accurately judge the results of the test operation, resulting in the judgment of the stability of calcium ions easily failing to achieve the purpose of the test.

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