Method for quick quantitative analysis of metal cations in oil field water

Abstract

The invention discloses a method for quick quantitative analysis of metal cations in oil field water. By complexometric titration, synchronous titration of calcium, magnesium, strontium, barium and iron in an oil field water sample is realized through solution acidity control and precipitation masking without special pretreatment. Due to reduction of steps of iron removal, heating, aging, filtering and diluting, operation steps are greatly reduced, operation time is greatly shortened, measurement result accuracy is improved, and operation efficiency is improved as well. The method is hopefully popularized and applied in oil field water quality analysis.

Description

technical field [0001] The invention relates to the field of oilfield water quality analysis, in particular to a rapid quantitative analysis method for metal cations in oilfield water. Background technique [0002] In the process of oilfield development, as the development time prolongs, the formation pressure gradually decreases, so water is injected into the reservoir through special injection wells to maintain or restore the reservoir pressure, so that the reservoir has a strong driving force, which is the key to improving the reservoir An important means and measure of the mining speed and recovery rate. Then, because the sources of injected water are generally more complex, including oil well produced water, surface water, shallow water, etc., the anion and cation contents in these different sources of water are also different, especially calcium, magnesium, strontium, barium, iron, etc. Ions, etc., if not analyzed and detected before injection, and properly treated, w...

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Problems solved by technology

[0003] The determination of cations in oilfield water mainly includes traditional complexometric titration and modern instrumental analysis methods, including ion chromatography and atomic spectroscopy, among which complexometric titration belongs to constant analysis with high accuracy, while ion chromatography and atomic spectroscopy belong to trace / trace analysis, although the sensitivity is high, the accuracy is relatively low. Therefore, the traditional complexometric titration method is generally used in the analysis of oilfield water samples, mainly based on the oil and gas industry standard ST / T 5329-94 "broken Recommended Indexes and Analysis Methods for Injection Water Quality in Clastic Reservoirs (hereinafter referred to as industry standards), but these methods generally involve operations such as iron removal, heating, aging, filtration, and dilution during the measurement process, which are not only cumbersome to operate, but also take a long time. Moreover, too many steps lead to an increase in measurement error, which is also a common problem in the analysis of oilfield water quality.

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