Method for detecting content of organic chlorine in thickened oil

Abstract

The invention relates to the technical field of heavy oil detection, in particular to a method for detecting the content of organic chlorine in heavy oil, which comprises the following steps: removing free water from to-be-detected heavy oil containing free water to obtain a heavy oil sample containing emulsified water, taking out the heavy oil sample containing emulsified water, adding a solvent which has a boiling point higher than 204 DEG C and is insoluble in water to obtain a diluted crude oil sample, and measuring the content of organic chlorine in heavy oil. The method comprises the following steps: centrifuging and dehydrating a thin oil sample to obtain a dehydrated crude oil sample, distilling the dehydrated crude oil sample to obtain fractions at the temperature of 204 DEG C or below, and detecting by using a micro-coulomb method to obtain the content of organic chlorine in the thickened oil. According to the method, the water-insoluble solvent with the boiling point higher than 204 DEG C is used for diluting the thickened oil, then the distillate oil with the boiling point higher than 204 DEG C is distilled out, and then the content of the organic chlorine in the distillate oil with the boiling point higher than 204 DEG C in the crude oil is determined by the microcoulometric method, so that the method has the advantages of high efficiency, simplicity and accurate measurement result, meets the GB / T 18612 requirement, and can realize rapid and accurate detection of the content of the organic chlorine in the water-containing thickened oil.

Description

Technical Field

[0001] This invention relates to the field of heavy oil detection technology, and is a method for detecting the content of organochlorine compounds in heavy oil. Background Technology

[0002] Currently, the domestic standard for detecting organochlorine content in crude oil is GB / T 18612-2011, "Determination of Organochlorine Content in Crude Oil - Microcoulometric Method." This method determines the organochlorine content in crude oil by measuring the organochlorine content in the distillate fraction below 204℃. This method is suitable for measuring dehydrated, purified crude oil intended for export. However, wellhead heavy oil containing free water cannot be directly distilled due to its high water content, and dehydration of water-containing heavy oil is difficult and time-consuming. Therefore, GB / T 18612 is not applicable to the detection of organochlorine content in water-containing heavy oil. To strengthen the source control of organochlorine in crude oil and the tracing of organochlorine pollution sources in oilfield enterprises, it is necessary to establish a method for determining the organochlorine content in water-containing heavy oil.

[0003] Chinese invention patent document CN107796861A discloses a method for detecting the organic chlorine content in crude oil containing free water. This method classifies crude oil containing free water into low-density, low-viscosity crude oil and high-density, high-viscosity crude oil based on viscosity and density, and solves the difficulties in detecting organic chlorine in crude oil containing free water by employing different dehydration and determination methods. However, the organic chlorine content measured is only for the fraction of crude oil below 320℃, which does not meet the requirements of GB / T 18612-2011 "Determination of Organic Chlorine Content in Crude Oil - Microcoulometric Method" for detecting the organic chlorine content in the fraction of crude oil below 204℃.

[0004] Chinese invention patent document CN108717077A discloses a method for detecting the organic chlorine content in crude oil. The method involves dehydrating the crude oil sample and removing the light fraction A1 (below 204°C) using a distillation apparatus. The light fraction A1 is then used to determine the organic chlorine (G) content using microcoulometrics. The fraction A2 (below 204°C) is used to determine the total chlorine content in the crude oil using microcoulometrics or potentiometry. The inorganic chlorine content in the fraction A2 is then determined by subtracting the inorganic chlorine content from the total chlorine content of fraction A2. The organic chlorine (F) is obtained by adding G to F. However, this method measures the total organic chlorine content in the crude oil, which does not meet the requirements of GB / T 18612-2011 "Determination of Organic Chlorine Content in Crude Oil - Microcoulometric Method" for detecting the organic chlorine content in distillate oils below 204°C. Furthermore, it does not address the difficulty of dehydrating water-containing heavy oils, which prevents direct distillation.

[0005] Therefore, it is necessary to develop a method suitable for detecting organochlorine content in heavy oil to solve the above problems. Summary of the Invention

[0006] This invention provides a method for detecting organochlorine content in heavy oil, overcoming the shortcomings of the prior art. It can effectively solve the problems of difficult dehydration and inability to directly distill water-containing heavy oil when detecting organochlorine content in existing heavy oil.

[0007] The technical solution of this invention is achieved through the following measures: a method for detecting the organochlorine content in heavy oil, comprising the following steps: S1, Remove the free water from the heavy oil containing free water to be tested, and obtain a heavy oil sample containing emulsified water; S2, Take out the heavy oil sample containing emulsified water, add a solvent with a boiling point above 204℃ that is insoluble in water, and obtain the diluted crude oil sample; S3, centrifuge the thin oil sample to remove water, and obtain a dehydrated crude oil sample; S4. The dehydrated crude oil sample is distilled to obtain the fraction below 204℃, and the organic chlorine content in the heavy oil is obtained by microcoulometric analysis.

[0008] The following are further optimizations and / or improvements to the above-mentioned technical solution: In step S2 above, the mass ratio of the emulsified water-containing heavy oil sample to the solvent dilution is 1 to 3: 3 to 1.

[0009] In step S2 above, the mass ratio of the emulsified water-containing heavy oil sample to the solvent dilution is 2:1.

[0010] The solvents mentioned above that have a boiling point above 204°C and are insoluble in water are one of n-dodecane, ethyl benzoate, and dibutyl oxalate.

[0011] In step S3 above, the water content of the dehydrated crude oil sample is less than 0.5%.

[0012] This invention uses a water-insoluble solvent with a boiling point above 204℃ to dilute heavy oil, then distills the fraction oil below 204℃, and then uses microcoulometric method to determine the organic chlorine content in the fraction oil below 204℃. It is efficient, simple, accurate in measurement results, and meets the requirements of GB / T 18612, and can realize rapid and accurate detection of organic chlorine content in water-containing heavy oil. Detailed Implementation

[0013] This invention is not limited to the following embodiments; specific implementation methods can be determined based on the technical solution of this invention and actual circumstances. Unless otherwise specified, all chemical reagents and chemical products mentioned in this invention are well-known and commonly used chemical reagents and chemical products in the prior art.

[0014] The present invention will be further described below with reference to embodiments: Example 1: A method for detecting the organochlorine content in this heavy oil, comprising the following steps: S1, Remove the free water from the heavy oil containing free water to be tested, and obtain a heavy oil sample containing emulsified water; S2, Take out the heavy oil sample containing emulsified water, add a solvent with a boiling point above 204℃ that is insoluble in water, and obtain the diluted crude oil sample; S3, centrifuge the thin oil sample to remove water, and obtain a dehydrated crude oil sample; S4. The dehydrated crude oil sample is distilled to obtain the fraction below 204℃, and the organic chlorine content in the heavy oil is obtained by microcoulometric analysis.

[0015] This invention uses a water-insoluble solvent (such as n-dodecane) with a boiling point above 204℃ to dilute the heavy oil sample, and then centrifuges or uses an electrostatic dehydrator to dehydrate the crude oil. This method can effectively remove water from the crude oil, and the operation is simple, time-saving, and does not affect the determination of organochlorine content after dehydration.

[0016] The method for detecting organochlorine content in water-containing heavy oil of the present invention realizes the detection of organochlorine content in crude oil containing free water, and the detection results are highly reliable with a relative error of less than 2%.

[0017] The experimental equipment and instruments used in this invention are relatively simple, making it easy to promote on a large scale and convenient for use by grassroots units.

[0018] Example 2: As an optimization of the above example, in step S2, the mass ratio of the emulsified water-containing heavy oil sample to the solvent dilution is 1 to 3:3 to 1, wherein, preferably, the mass ratio of the emulsified water-containing heavy oil sample to the solvent dilution is 2:1.

[0019] Example 3: As an optimization of the above example, the solvent with a boiling point above 204°C and insoluble in water is one of n-dodecane, ethyl benzoate and dibutyl oxalate.

[0020] Example 4: As an optimization of the above example, in step S3, the water content of the dehydrated crude oil sample is less than 0.5%.

[0021] Nine samples of heavy oil from a certain oil field, namely heavy oil 1 to 9, were tested for the content of organochlorine in the oil using the method of the present invention.

[0022] Example 5: A method for detecting the organochlorine content in this heavy oil, comprising the following steps: S1, Remove the free water from the heavy oil containing free water to be tested, and obtain a heavy oil sample containing emulsified water; S2, Take out the heavy oil sample containing emulsified water, add a solvent with a boiling point above 204℃ and insoluble in water (n-dodecane commercially available from Tianjin Kemei Chemical Reagent Co., Ltd.) to obtain a diluted crude oil sample, wherein the mass ratio of the heavy oil sample containing emulsified water to the solvent dilution is 2:1. S3, the thin oil sample is centrifuged to dehydrate it, and a dehydrated crude oil sample (water content of 0.3%) is obtained. During dehydration, the centrifuge speed is 1500 r / min and the centrifugation time is 5 min. S4. The dehydrated crude oil sample is distilled to obtain the fraction below 204℃, and the organic chlorine content in the heavy oil is obtained by microcoulometric analysis.

[0023] In Example 5, n-dodecane is a colorless liquid with a melting point of -9.6°C, a boiling point of 216.3°C, and a density of 0.753 g / cm³. 3 It has a viscosity of 3.8 mPa·s at 20℃, is insoluble in water, and readily soluble in ethanol, ether, acetone, chloroform, carbon tetrachloride, and benzene. It is used as an intermediate and solvent in organic synthesis.

[0024] In Example 5 of this invention, the actual detection results of organochlorine content in heavy oil from a certain oilfield are shown in Table 1.

[0025] Example 6: A method for detecting the organochlorine content in this heavy oil, comprising the following steps: S1, Remove the free water from the heavy oil containing free water to be tested, and obtain a heavy oil sample containing emulsified water; S2, Take out the heavy oil sample containing emulsified water, add a solvent with a boiling point above 204℃ and insoluble in water (n-dodecane commercially available from Tianjin Kemei Chemical Reagent Co., Ltd.) to obtain a diluted crude oil sample, wherein the mass ratio of the heavy oil sample containing emulsified water to the solvent dilution is 3:1. S3, the thin oil sample is centrifuged to dehydrate it, and a dehydrated crude oil sample (water content of 0.3%) is obtained. During the dehydration, the centrifuge speed is 3000 r / min and the centrifugation time is 30 min. S4. The dehydrated crude oil sample is distilled to obtain the fraction below 204℃, and the organic chlorine content in the heavy oil is obtained by microcoulometric analysis.

[0026] In Example 6, n-dodecane is a colorless liquid with a melting point of -9.6°C, a boiling point of 216.3°C, and a density of 0.753 g / cm³. 3 It has a viscosity of 3.8 mPa·s at 20℃, is insoluble in water, and readily soluble in ethanol, ether, acetone, chloroform, carbon tetrachloride, and benzene. It is used as an intermediate and solvent in organic synthesis.

[0027] In Example 6 of this invention, the actual detection results of organochlorine content in heavy oil from a certain oilfield are shown in Table 2.

[0028] Example 7: A method for detecting the organochlorine content in this heavy oil, comprising the following steps: S1, Remove the free water from the heavy oil containing free water to be tested, and obtain a heavy oil sample containing emulsified water; S2, Take out the heavy oil sample containing emulsified water, add a solvent with a boiling point above 204℃ and insoluble in water (ethyl benzoate commercially available from Tianjin Kemei Chemical Reagent Co., Ltd.) to obtain a diluted crude oil sample, wherein the mass ratio of the heavy oil sample containing emulsified water to the solvent dilution is 1:1. S3, the thin oil sample is centrifuged to dehydrate it, and a dehydrated crude oil sample (water content of 0.3%) is obtained. During the dehydration, the centrifuge speed is 3000 r / min and the centrifugation time is 15 min. S4. The dehydrated crude oil sample is distilled to obtain the fraction below 204℃, and the organic chlorine content in the heavy oil is obtained by microcoulometric analysis.

[0029] In Example 7, ethyl benzoate is a colorless liquid with a melting point of -34.6°C, a boiling point of 212.6°C, and a density of 1.05 g / cm³. 3 .

[0030] In Example 7 of this invention, the actual detection results of organochlorine content in heavy oil from a certain oilfield are shown in Table 3.

[0031] Example 8: A method for detecting the organochlorine content in this heavy oil, comprising the following steps: S1, Remove the free water from the heavy oil containing free water to be tested, and obtain a heavy oil sample containing emulsified water; S2, Take out the heavy oil sample containing emulsified water, add a solvent with a boiling point above 204℃ and insoluble in water (dibutyl oxalate commercially available from Tianjin Kemei Chemical Reagent Co., Ltd.) to obtain a diluted crude oil sample, wherein the mass ratio of the heavy oil sample containing emulsified water to the solvent dilution is 1:1. S3, the thin oil sample is centrifuged to dehydrate it, and a dehydrated crude oil sample (water content of 0.3%) is obtained. During the dehydration, the centrifuge speed is 3000 r / min and the centrifugation time is 15 min. S4. The dehydrated crude oil sample is distilled to obtain the fraction below 204℃, and the organic chlorine content in the heavy oil is obtained by microcoulometric analysis.

[0032] In Example 8, dibutyl oxalate was a colorless liquid with a melting point of -13°C, a boiling point of 355°C, and a density of 0.987 g / cm³. 3 .

[0033] In Example 8 of this invention, the actual detection results of the organochlorine content in heavy oil from a certain oilfield are shown in Table 4.

[0034] As can be seen from Tables 1 to 4, the method for detecting organochlorine content in heavy oil according to the present invention can effectively remove water from heavy oil containing emulsified water using the high-boiling-point solvent dilution method. The determination value of organochlorine content in the dehydrated crude oil is highly reliable, the detection time is short, and the relative error with the GB / T18612-2011 method is within 2%.

[0035] In summary, this invention uses a water-insoluble solvent with a boiling point above 204℃ to dilute heavy oil, then distills the fraction oil below 204℃, and then uses microcoulometric method to determine the organic chlorine content in the fraction oil below 204℃ in the crude oil. This method is efficient, simple, provides accurate measurement results, and meets the requirements of GB / T 18612, enabling rapid and accurate detection of organic chlorine content in water-containing heavy oil.

[0036] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A method for detecting organochlorine content in heavy oil, characterized in that... Includes the following steps: S1, Remove the free water from the heavy oil containing free water to be tested, and obtain a heavy oil sample containing emulsified water; S2, Take out the heavy oil sample containing emulsified water, add a solvent with a boiling point above 204℃ that is insoluble in water, and obtain the diluted crude oil sample; S3, centrifuge the thin oil sample to remove water, and obtain a dehydrated crude oil sample; S4. The dehydrated crude oil sample is distilled to obtain the fraction below 204℃, and the organic chlorine content in the heavy oil is obtained by microcoulometric analysis.

2. The method for detecting organochlorine content in heavy oil according to claim 1, characterized in that... In step S2, the mass ratio of the emulsified water-containing heavy oil sample to the solvent dilution is 1 to 3: 3 to 1.

3. The method for detecting organochlorine content in heavy oil according to claim 2, characterized in that... In step S2, the mass ratio of the emulsified water-containing heavy oil sample to the solvent dilution is 2:

1.

4. The method for detecting organochlorine content in heavy oil according to claim 1, 2, or 3, characterized in that... The solvent with a boiling point above 204℃ and insoluble in water is one of n-dodecane, ethyl benzoate, and dibutyl oxalate.

5. The method for detecting organochlorine content in heavy oil according to claim 1, 2, or 3, characterized in that... In step S3, the conditions for centrifugal dehydration include: a temperature of 50°C to 60°C, a rotation speed of 1000 r / min to 3000 r / min, and a dehydration time of 5 min to 30 min.

6. The method for detecting organochlorine content in heavy oil according to claim 4, characterized in that... In step S3, the conditions for centrifugal dehydration include: a temperature of 50°C to 60°C, a rotation speed of 1000 r / min to 3000 r / min, and a dehydration time of 5 min to 30 min.

7. The method for detecting organochlorine content in heavy oil according to claim 1, 2, 3, or 6, characterized in that... In step S3, the water content of the dehydrated crude oil sample is less than 0.5%.

8. The method for detecting organochlorine content in heavy oil according to claim 4, characterized in that... In step S3, the water content of the dehydrated crude oil sample is less than 0.5%.

9. The method for detecting organochlorine content in heavy oil according to claim 5, characterized in that... In step S3, the water content of the dehydrated crude oil sample is less than 0.5%.

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