CN112147241A - Method for detecting normal alkane in oil field water sample - Google Patents
Method for detecting normal alkane in oil field water sample Download PDFInfo
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- CN112147241A CN112147241A CN201910575732.6A CN201910575732A CN112147241A CN 112147241 A CN112147241 A CN 112147241A CN 201910575732 A CN201910575732 A CN 201910575732A CN 112147241 A CN112147241 A CN 112147241A
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- water sample
- oil field
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- thermal desorption
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
- G01N30/08—Preparation using an enricher
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
- G01N2030/062—Preparation extracting sample from raw material
Abstract
The invention discloses a method for detecting normal paraffin in an oil field water sample, which is characterized by comprising the following steps: placing the magnetic stirring rod coated with the PDMS coating in a sealed oil field water sample under the condition of magnetic stirring to adsorb normal alkane in the oil field water sample, taking out the magnetic stirring rod after adsorption is finished, removing surface moisture, and placing the magnetic stirring rod in a thermal desorption pipe; and sealing two ends of the thermal desorption tube, putting the thermal desorption tube into a thermal desorption instrument, and carrying out chromatographic mass spectrometry to obtain the n-alkane content in the water sample of the oil field. The method has the advantages of simple and convenient operation, large pretreatment flux, high adsorption efficiency, no need of solvent, environmental friendliness and stable and reliable detection result, and provides a reliable technical means for the application of the earth surface oil gas geochemical exploration technology.
Description
Technical Field
The invention belongs to the field of geochemical exploration of surface oil and gas, and particularly relates to a method for detecting normal paraffin in an oil field water sample.
Background
The chemical exploration in wells and oil field water research at home and abroad proves that the liquid hydrocarbon (C) with medium molecular weight6-C15) And C1-C5The same gaseous hydrocarbons can also vertically move, but the moving capacity is weak, the amount of the hydrocarbons reaching the near surface is smaller and smaller along with the increase of the buried depth of the oil and gas reservoir, and the content of the hydrocarbons is more and more difficult to detect on the near surface by the conventional surface detection technology. With the progress of modern testing technology, people can detect the extremely low content (10) more and more accurately-6Even 10, respectively-9) Is present.
In recent years, the stirring rod adsorption technology is experimentally applied in the fields of environmental monitoring and food, has the advantages of short adsorption time, less solvent consumption and higher recovery rate than the traditional extraction technology, and quickly replaces the traditional Soxhlet extraction technology, ultrasonic extraction technology and other technologies. In the field of surface oil and gas exploration, a solid phase microextraction technology is developed to detect benzene series which is easy to volatilize in soil, but when trace alkane in water is extracted, a stirrer can generate competitive adsorption in Fiber needle type solid phase microextraction (Fiber-SPME), and the volume of an adsorption stationary phase is small. The normal paraffin is one of indexes of surface oil and gas exploration, but the normal paraffin is insoluble in water, so that the normal paraffin content in water is much less and less, and the content of the normal paraffin is difficult to detect near the surface by the conventional surface detection technology.
Aiming at the problems in the prior art, the invention needs to invent a method for adsorbing trace normal paraffin in water, and meets the requirements of scientific research and production.
Disclosure of Invention
The invention aims to solve the problems in the prior art, provides a method for adsorbing trace normal paraffin in water by using a stirring rod through a stirring rod adsorption-thermal desorption technology and GC/MS analysis, and meets the requirements of scientific research and production.
In order to achieve the above object, the present invention provides a method for detecting normal paraffin in an oil field water sample, the method comprising:
(1) placing the magnetic stirring rod coated with the PDMS coating in a sealed oil field water sample, adsorbing normal alkane in the oil field water sample under the magnetic stirring condition, taking out the magnetic stirring rod after adsorption is finished, removing surface moisture, and placing the magnetic stirring rod in a thermal desorption pipe;
(2) and sealing two ends of the thermal desorption tube, putting the thermal desorption tube into a thermal desorption instrument, and carrying out chromatographic mass spectrometry to obtain the n-alkane content in the water sample of the oil field.
In the invention, the extraction stationary phase is Polydimethylsiloxane (PDMS), and the adsorption stirring rod completes stirring, thereby avoiding competitive adsorption of a stirring element in Fiber-SPME.
Preferably, the detection method further comprises: before the magnetic stirring rod coated with the PDMS coating is placed in a sealed oilfield water sample, the stirring rod coated with the PDMS coating is placed in a thermal desorption aging device for aging or is soaked in an organic solvent. The soaking with the organic solvent is also for aging, which is to remove hydrocarbons and other impurities.
Preferably, the aging temperature is 250-350 ℃, and the aging time is 1.5-2.5 h.
Preferably, the organic solvent is acetonitrile. The stirring bar coated with PDMS coating is typically soaked in 100% acetonitrile for 10-12 h.
Preferably, the thickness of the PDMS coating of the magnetic stirring rod coated with the PDMS coating is 0.8-1.2 mm.
Preferably, the rotation speed of the magnetic stirring is 800-1200 rpm, the temperature of the magnetic stirring is 45-55 ℃, and the adsorption time is 2-20 min, more preferably 10-18 min.
As a preferable scheme, the content of the normal alkane in the water sample of the oil field is trace, which can be understood as less than or equal to 0.0001%.
Preferably, the thermal desorption detection conditions include:
the temperature of the transmission line is 140-160 ℃, the initial temperature of thermal desorption is 45-55 ℃, the heating rate is 50-70 ℃/min, the detection temperature is 240-260 ℃, and the holding time is 100-140 s.
As a preferable scheme, when the chromatographic mass spectrometry is carried out, the temperature of a CIS sample inlet is-45 to-55 ℃ when the CIS sample inlet is cooled, the temperature is increased to 180 to 220 ℃ at the temperature increase rate of 18 to 22 ℃/s when the CIS sample inlet is fed, and then the temperature is maintained for 40 to 80 s.
The method utilizes a magnetic stirring rod coated with a PDMS coating to adsorb trace n-alkanes in water, adsorbs the n-alkanes for a certain time at a certain stirring rotating speed and adsorption temperature, and then sequentially puts the adsorbed samples into a desorption tube of a thermal desorption instrument for chromatographic mass spectrometry detection.
In the invention, the extraction stationary phase is Polydimethylsiloxane (PDMS), and the adsorption stirring rod completes stirring, thereby avoiding competitive adsorption of a stirring element in Fiber-SPME. The volume of the extraction stationary phase is generally 55-250 microliter, which is more than 50 times larger than that of the Fiber SPME extraction stationary phase, so the enrichment factor is correspondingly improved, and the method is suitable for analyzing trace components in a sample.
The method has the advantages of simple and convenient operation, large pretreatment flux, high adsorption efficiency, no need of solvent, environmental friendliness and stable and reliable detection result, and provides a reliable technical means for the application of the earth surface oil gas geochemical exploration technology.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, wherein like reference numerals generally represent like parts.
FIG. 1 shows a schematic flow chart of a method for detecting normal paraffin in an oil field water sample.
FIG. 2 shows the results C of the chromatographic mass spectrometry detection at different extraction times in examples 1-2 of the present invention5-C10。
FIG. 3 shows the results C of the chromatographic mass spectrometry with different stirring rates in example 3 of the present invention5-C10。
Description of reference numerals:
1-a magnetic stirrer; 2-a flat bottom flask; 3-rubber plug; 4-a magnetic stirring rod; 5-heat desorption pipe; 6-thermal desorption instrument; 7-a chromatographic mass spectrometer; 8-a computer.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
FIG. 1 shows a schematic flow chart of a method for detecting normal paraffin in an oil field water sample.
The magnetic stirring rod 4 coated with the PDMS coating is placed in a flat-bottomed flask 2 (which can be placed on a magnetic stirrer 1), sealed (if a rubber plug 3 in the figure 1 is used), and after a period of adsorption, the magnetic stirring rod 4 is taken out, and after water on the surface is absorbed, the magnetic stirring rod is placed in a thermal desorption tube 5, and two ends are sealed. The adsorbed sample is then put into a thermal desorption apparatus 6 for gas chromatography-mass spectrometry (using a mass spectrometer 7 and a computer 8).
The normal alkane mixed standard components in the examples of the invention are shown in table 1.
TABLE 1 Normal alkane mixed standards (Supelco Co Ltd.)
Example 1:
measuring 100mL of an oil field water sample (0.2 mu L of normal alkane mixed standard sample is added into the water sample) by using a liquid transfer gun, putting the oil field water sample into a 500mL flat-bottomed flask, putting an aged (stirring rod coated with a PDMS coating in a thermal desorption aging apparatus for aging at 350 ℃ for 2h) magnetic stirring rod coated with the PDMS coating and used for adsorbing normal alkane, sealing and shaking uniformly, setting the rotating speed of magnetic stirring to be 1000rpm, and setting the temperature of magnetic stirring to be 50 ℃. After adsorbing for 15min, the stirring rod was quickly taken out, the surface water was removed with filter paper, placed in a thermal desorption tube, and both ends were sealed. And then putting the adsorbed sample into a thermal desorption instrument for chromatographic mass spectrometry detection, wherein the detection result is shown in figure 2.
Wherein, the thermal desorption detection conditions are as follows: the temperature of a transmission line is 150 ℃, the initial temperature of thermal desorption is 50 ℃, the temperature rises to 250 ℃ at a speed of 60 ℃/min, the temperature is kept for 2min, the temperature of a CIS sample inlet is kept at 50 ℃ below zero, the temperature rises to 200 ℃ at a temperature rise speed of 20 ℃/s during sample injection, and then the temperature is kept for 1 min.
Example 2:
the difference from example 1 is that the adsorption time is 2min, 5min, 10min and 20min, and the detection result is shown in fig. 2.
Example 3:
the difference from example 1 was that the rotation speeds of the magnetic stirrer were set to 400rpm, 600rpm, 800rpm, 1000rpm, and 1200rpm, respectively, and the results of the measurements were as shown in FIG. 3.
Example 4:
the difference from example 1 is that the PDMS coated magnetic stir bar was not aged and interfered with other hydrocarbons and impurities.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (10)
1. A method for detecting normal paraffin in an oil field water sample is characterized by comprising the following steps:
(1) placing the magnetic stirring rod coated with the PDMS coating in a sealed oil field water sample, adsorbing normal alkane in the oil field water sample under the magnetic stirring condition, taking out the magnetic stirring rod after adsorption is finished, removing surface moisture, and placing the magnetic stirring rod in a thermal desorption pipe;
(2) and sealing two ends of the thermal desorption tube, putting the thermal desorption tube into a thermal desorption instrument, and carrying out chromatographic mass spectrometry to obtain the n-alkane content in the water sample of the oil field.
2. The method for detecting n-alkanes in water samples of oil fields as claimed in claim 1, wherein said method further comprises:
before the stirring rod coated with the PDMS coating is placed in a sealed oilfield water sample, the magnetic stirring rod coated with the PDMS coating is placed in a thermal desorption aging device for aging or is soaked in an organic solvent.
3. The method for detecting the normal paraffin in the water sample of the oilfield according to claim 2, wherein the aging temperature is 250-350 ℃, and the aging time is 1.5-2.5 h.
4. The method for detecting n-alkanes in water samples of oil fields as claimed in claim 2, wherein said organic solvent is acetonitrile.
5. The method for detecting the normal paraffin in the water samples in the oil field as claimed in claim 1, wherein the PDMS coating of the magnetic stirring rod coated with the PDMS coating has a thickness of 0.8-1.2 mm.
6. The method for detecting the normal paraffin in the water sample of the oilfield according to claim 1, wherein the rotation speed of the magnetic stirring is 800-1200 rpm, the temperature of the magnetic stirring is 45-55 ℃, and the adsorption time is 2-20 min.
7. The method for detecting the normal paraffin in the water sample of the oilfield according to claim 6, wherein the adsorption time is 10-18 min.
8. The method for detecting the normal paraffin in the water sample of the oil field as claimed in claim 1, wherein the content of the normal paraffin in the water sample of the oil field is less than or equal to 0.0001%.
9. The method for detecting the normal paraffin hydrocarbons in the water samples of the oil field as claimed in claim 1, wherein the thermal desorption detection conditions comprise:
the temperature of the transmission line is 140-160 ℃, the initial temperature of thermal desorption is 45-55 ℃, the heating rate is 50-70 ℃/min, the detection temperature is 240-260 ℃, and the holding time is 100-140 s.
10. The method for detecting the normal paraffin in the water sample of the oilfield according to claim 1, wherein when the chromatographic mass spectrometry is carried out,
the temperature of a CIS injection port is-45 to-55 ℃ when the CIS is cooled, the temperature is increased to 180 to 220 ℃ at the temperature increase rate of 18 to 22 ℃/s when the CIS is injected, and then the CIS is kept for 40 to 80 s.
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| CN201910575732.6A CN112147241A (en) | 2019-06-28 | 2019-06-28 | Method for detecting normal alkane in oil field water sample |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160223440A1 (en) * | 2013-03-15 | 2016-08-04 | The Florida International University Board Of Trustees | Fabric Phase Sorptive Extractors |
| CN109358149A (en) * | 2018-11-03 | 2019-02-19 | 浙江环境监测工程有限公司 | The fast quantitative measurement method for detecting of polycyclic aromatic hydrocarbon in a kind of surface water |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160223440A1 (en) * | 2013-03-15 | 2016-08-04 | The Florida International University Board Of Trustees | Fabric Phase Sorptive Extractors |
| CN109358149A (en) * | 2018-11-03 | 2019-02-19 | 浙江环境监测工程有限公司 | The fast quantitative measurement method for detecting of polycyclic aromatic hydrocarbon in a kind of surface water |
Non-Patent Citations (3)
| Title |
|---|
| CECILE KONN ET AL.: "Characterisation of dissolved organic compounds in hydrothermal fluids by stir bar sorptive extraction-gas chomatography-mass spectrometry. Case study: the Rainbow field (36°N, Mid-Atlantic Ridge)", 《GEOCHEMICAL TRANSACTIONS》, 31 December 2012 (2012-12-31), pages 1 - 19 * |
| 刘文民 等: "固相微萃取新技术在水分析中的应用", 《生命科学仪器》, 31 December 2004 (2004-12-31), pages 12 - 16 * |
| 刘文民 等: "溶胶凝胶法制备固相微萃取搅拌棒", 《分析化学》, 31 January 2005 (2005-01-31), pages 45 - 49 * |
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Application publication date: 20201229 |