US20230273120A1 - Determination of total crude oil in water by absorbance spectrophotometry - Google Patents
Determination of total crude oil in water by absorbance spectrophotometry Download PDFInfo
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- US20230273120A1 US20230273120A1 US17/682,243 US202217682243A US2023273120A1 US 20230273120 A1 US20230273120 A1 US 20230273120A1 US 202217682243 A US202217682243 A US 202217682243A US 2023273120 A1 US2023273120 A1 US 2023273120A1
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- 239000010779 crude oil Substances 0.000 title claims abstract description 111
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 76
- 238000002835 absorbance Methods 0.000 title claims abstract description 59
- 238000002798 spectrophotometry method Methods 0.000 title description 6
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims abstract description 86
- 239000008096 xylene Substances 0.000 claims abstract description 86
- 238000005259 measurement Methods 0.000 claims abstract description 45
- 238000000034 method Methods 0.000 claims abstract description 45
- 239000012482 calibration solution Substances 0.000 claims abstract description 30
- 238000011088 calibration curve Methods 0.000 claims abstract description 15
- 238000005191 phase separation Methods 0.000 claims abstract description 3
- 239000000243 solution Substances 0.000 claims description 22
- 239000012267 brine Substances 0.000 claims description 15
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims description 15
- 238000000622 liquid--liquid extraction Methods 0.000 claims description 9
- 238000000638 solvent extraction Methods 0.000 claims description 9
- 238000003908 quality control method Methods 0.000 claims description 8
- 238000000862 absorption spectrum Methods 0.000 claims description 4
- 239000012085 test solution Substances 0.000 claims description 4
- 238000005119 centrifugation Methods 0.000 claims description 3
- 238000012417 linear regression Methods 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 238000012935 Averaging Methods 0.000 claims description 2
- 239000010410 layer Substances 0.000 description 18
- 239000003921 oil Substances 0.000 description 11
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 8
- 238000010586 diagram Methods 0.000 description 8
- 238000012360 testing method Methods 0.000 description 7
- 238000004364 calculation method Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 238000002360 preparation method Methods 0.000 description 5
- 238000000926 separation method Methods 0.000 description 5
- 239000012044 organic layer Substances 0.000 description 4
- 239000011780 sodium chloride Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 2
- 239000001110 calcium chloride Substances 0.000 description 2
- 229910001628 calcium chloride Inorganic materials 0.000 description 2
- LLSDKQJKOVVTOJ-UHFFFAOYSA-L calcium chloride dihydrate Chemical compound O.O.[Cl-].[Cl-].[Ca+2] LLSDKQJKOVVTOJ-UHFFFAOYSA-L 0.000 description 2
- 229940052299 calcium chloride dihydrate Drugs 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- -1 purity ≥98.5% Chemical compound 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000004611 spectroscopical analysis Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000000692 Student's t-test Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
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- 238000012545 processing Methods 0.000 description 1
- 238000011002 quantification Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000012353 t test Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/33—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using ultraviolet light
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/40—Concentrating samples
- G01N1/4077—Concentrating samples by other techniques involving separation of suspended solids
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/27—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands using photo-electric detection ; circuits for computing concentration
- G01N21/274—Calibration, base line adjustment, drift correction
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/18—Water
- G01N33/1826—Water organic contamination in water
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/18—Water
- G01N33/1826—Water organic contamination in water
- G01N33/1833—Oil in water
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/40—Concentrating samples
- G01N1/4077—Concentrating samples by other techniques involving separation of suspended solids
- G01N2001/4083—Concentrating samples by other techniques involving separation of suspended solids sedimentation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N2201/127—Calibration; base line adjustment; drift compensation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2201/00—Features of devices classified in G01N21/00
- G01N2201/12—Circuits of general importance; Signal processing
- G01N2201/127—Calibration; base line adjustment; drift compensation
- G01N2201/12746—Calibration values determination
Definitions
- the present disclosure is directed to a method for the quantitative determination of total crude oil in water by absorbance spectrophotometry.
- WOSP water oil separation plant
- An embodiment described in examples herein provides a method for quantifying a crude oil in water.
- the method includes selecting a ultraviolet/visible (UV/Vis) wavelength to perform a measurement, preparing calibration solutions in xylene, and preparing a calibration curve from the calibration solutions.
- a sample is prepared including extracting the crude oil from the water in a two-phase separation with xylene.
- An absorbance of the sample in the xylene is measured at the UV/Vis wavelength.
- a concentration of the crude oil in the water is calculated from the absorbance.
- FIG. 1 is a process flow diagram of a method for determining total crude oil in water by absorbance spectroscopy spectrophotometry.
- FIG. 2 is a schematic diagram of the wavelength selection process.
- FIG. 3 is a polynomial interpolation of absorbance for a 100 ppm solution of a first crude oil in xylene.
- FIG. 4 is a polynomial interpolation of absorbance for a 100 ppm solution of a second crude oil in xylene.
- FIG. 5 is a schematic diagram of the calibration procedure.
- FIG. 6 is a plot of the calibration curve for the first crude oil.
- FIG. 7 is a plot of the calibration curve for the second crude oil.
- FIG. 8 is a schematic diagram of the sample preparation and measurement procedure.
- a method for the quantitative determination of crude oil in water by UV-visible spectrophotometry is provided.
- a corresponding crude oil sample is analyzed by the spectrophotometer at a range of wavelength values to determine the wavelength value that will be used in calibration and sample measurement.
- an oil-soluble solvent, xylene is introduced to the water samples for liquid-liquid extraction (LLE).
- LLE liquid-liquid extraction
- the organic layer is then separated from water.
- the concentration of total crude oil in the organic layer is determined by external calibration in the ppm level using UV-Visible spectrophotometry at the chosen wavelength value. Subsequently, the concentration of total crude oil in water is calculated.
- FIG. 1 is a process flow diagram of a method 100 for determining total crude oil in water by absorbance spectroscopy spectrophotometry.
- the method 100 begins at block 102 with selecting a wavelength in the UV-Visible spectrum for the measurement. As different crude oil samples have different compositions, selecting an appropriate wavelength will increase both the accuracy and the precision of the measurement. A corresponding crude oil sample is analyzed by the spectrophotometer at a range of wavelength values to determine the wavelength value that will be used in calibration and sample measurement. The selection of the wavelength is discussed further with respect to FIGS. 2 - 4 of the examples.
- calibration solutions are mixed in xylene at a number of concentrations.
- concentrations may be selected to cover the expected range of oil concentrations.
- the calibration solutions are used to determine a calibration curve. The mixing of the calibration solutions and the determination of the calibration curve are discussed further with respect to FIGS. 5 - 7 of the examples.
- the sample is prepared for measurement.
- An oil-soluble solvent, xylene is introduced to the water samples for liquid-liquid extraction (LLE), for example, in a separatory funnel.
- LLE liquid-liquid extraction
- the organic layer is then separated from water and centrifuged to remove solid impurities and water droplets.
- the absorbance of the sample is measured at the selected wavelength.
- the concentration of total crude oil in the organic layer is determined by from the calibration curves and the absorbance of the sample. The measurement of the absorbance of the sample and the calculation of the crude oil concentration are discussed further with respect to FIG. 8 of the example.
- the method 100 described herein uses the following equipment (or equivalent). Weights are measured on a calibrated analytical balance capable of weighing up to 0.1 mg, for example, a Mettler model AT-261 available from Mettler-Toledo of Columbus, Ohio, USA.
- the centrifuge used for the purification of the oil sample after extraction can be a Seta Oil Test Centrifuge 90000-0 (operating range: 300-2800 rpm) available from Stanhope-Seta of Chertsey, Surrey, UK.
- the spectrophotometer used for the UV-Vis measurements was a Jenway 6300 UV-Vis Spectrophotometer available from Cole-Panner of Stone, Staffordshire, UK.
- the lab equipment used for the method 100 includes a 500 mL separatory funnel, 15 mL glass test tubes, 10 mL volumetric flasks, 50 mL volumetric flasks, adjustable volume pipettes, and a spectrophotometer cuvette. Disposable pipette tips were also used. As some measurements may be made in the ultraviolet range, the cuvette may be a 1 cm ⁇ 1 cm quartz cuvette.
- the chemicals used in the method 100 includes xylene, purity ⁇ 98.5%, sodium chloride, purity ⁇ 99.6%, and calcium chloride dihydrate, purity ⁇ 99.0%.
- a corresponding crude oil sample from the same source of the crude oil in the water samples is used to select the measurement wavelength and prepare the calibration samples.
- two crude oil samples were used to demonstrate the techniques, termed crude oil A and crude oil B, herein.
- FIG. 2 is a schematic diagram of the wavelength selection process. This may correspond to block 102 of the method 100 of FIG. 1 .
- the corresponding crude oil 202 and xylene tool for were combined to form the solution 206 of crude oil in xylene.
- the solution 206 were measured in the spectrophotometer 208 to generate a number of values of absorbance at different wavelengths.
- a scanning spectrophotometer may be used to generate a spectrum.
- the spectrophotometer was powered and allowed to warm until the absorbance (or any other reading, such as % T or CONC) reading was stable.
- the corresponding crude oil 202 was taken from the same source of crude oil as would be present in the water samples. 0.001 g of the corresponding crude oil was added to in a 10 mL volumetric flask and diluted to the mark with xylene. The flask was shaken to prepare a 100 ppm solution (other concentrations can be used).
- ABS absorbance
- Xylene was added to the cuvette and the outside walls of the cuvette were cleaned with a tissue paper, then placed in the spectrophotometer 208 (rinsing the cuvette walls was performed). The xylene measurement was used as the blank. A wavelength value was selected and the calibrate operation was selected. Blank calibrations were performed for each selected wavelength.
- the cuvette was filled with the prepared crude oil solution and placed in the spectrophotometer 208 after the outside of the cuvette was rinsed. The absorbance was recorded, and the measurements were repeated at different wavelengths to cover the range of 320-1000 nm.
- FIGS. 3 and 4 A wavelength value was selected to have high relative absorbance. This will result in an external calibration line with a good repeatability, r 2 >0.995, and substantially low percentage error, ⁇ 10%.
- 450 nm was chosen for crude oil A, which is near to the maximum absorbance wavelength
- 350 nm was chosen for crude oil B, which is the maximum absorbance wavelength.
- FIGS. 3 and 4 This is shown in FIGS. 3 and 4 .
- FIG. 3 is a polynomial interpolation of absorbance for a 100 ppm solution of a first crude oil in xylene.
- FIG. 4 is a polynomial interpolation of absorbance for a 100 ppm solution of a second crude oil in xylene.
- FIG. 5 is a schematic diagram of the calibration procedure. This may correspond to blocks 104 and 106 of FIG. 1 . Like numbered items are as described with respect to FIG. 2 .
- the corresponding crude oil 202 was mixed with xylene 204 to form a series of calibration solutions, for example, at 10 ppm 502, 20 ppm 504, 40 ppm 506, 60 ppm 508, 80 ppm 510, 100 ppm 512, 200 ppm 514, 300 ppm 516, 400 ppm 518, 800 ppm 520, and 1000 ppm 522, among others.
- 0.0001 g of the corresponding crude oil was added to a 10 mL volumetric flask and diluted to the mark with xylene. The flask was then shaken to prepare a 10 ppm solution (add 0.0002 g of crude oil instead of 0.0001 g for 20 ppm . . . etc.).
- the specific concentration selected may depend on the expected concentration of the crude oil in water.
- the absorbance of each of the calibration solutions 502 - 522 are then measured at the selected wavelength in the spectrophotometer 208 as described with respect to the wavelength selection process. The calculations used to determine the concentrations are described below.
- a cuvette with xylene was placed in the instrument and the calibrate button was pressed.
- the cuvette was then filled with a prepared crude oil calibration solution and placed in the spectrophotometer (rinsing is recommended).
- the absorbance of the solution was measured (3 repeated measurements for each calibration solution) and the results were recorded. The absorbance of the blank was checked after every 6 to 9 measurements to ensure it was at zero.
- the calibration results for the first crude oil sample (A) are shown in Table 1.
- FIG. 6 is a plot of the calibration curve for the first crude oil.
- FIG. 7 is a plot of the calibration curve for the second crude oil. For both crude oils, it was confirmed that the r 2 is 0.995 or higher.
- FIG. 8 is a schematic diagram of the sample preparation and measurement procedure. This corresponds to blocks 108 and 110 of FIG. 1 . Like numbered items are as described with respect to FIG. 2 .
- a water sample 802 was collected in a water sample bottle.
- the water sample bottle, including the water sample 802 was weighed and the total mass of the bottle was recorded.
- the water sample 802 was transferred to a separatory funnel 804 and the mass of the empty bottle was recorded to determine the mass of the water sample 802 .
- xylene 204 was added to the separatory funnel 804 and the amount of the added xylene 204 was recorded.
- the volume of the added xylene 204 depends on the amount of crude oil present in the water sample. However, the volume of the added xylene 204 generally equals about 10 vol. % to about 34 vol. % of the water sample 802 .
- the separatory funnel 804 was vigorously shaken, and the bottom, or water, layer was discarded.
- the top, or xylene, layer was transferred to a test tube.
- the solution is diluted with additional xylene if the expected concentration is outside of the calibration range.
- test tube was placed in a centrifuge 806 , and centrifuged for 5 minutes at 1500 rpm to remove water droplets and solids in the xylene layer.
- a pipet was used to transfer the xylene layer to the cuvette, avoiding the bottom of the test tube and the wall of the test tube, as the centrifugation pushed the water and solids down or to the side.
- the cuvette was placed in the spectrophotometer 208 , and the absorbance of the separated xylene layer was measured at the same wavelength used in the calibration. Three repeated measurements were run for each sample, and an average was calculated.
- Quality control samples were prepared to determine the accuracy and precision of the method.
- 1 g of sodium chloride was added to a 50 mL volumetric flask and diluted to the mark with distilled water. The solution was shaken vigorously, resulting in a 2 wt. % NaCl solution (mass percentage).
- the two prepared solutions were mixed, to prepare 100 mL of a 1 wt. % NaCl, 3 wt. % CaCl 2 ) brine solution.
- 0.001 g of the corresponding crude oil was added to a 10 mL volumetric flask, and diluted with the prepared brine to the mark and shaken.
- This prepared a 100 ppm mixture for the tests, although any concentration in the calibration range 10-1000 ppm can be used.
- the sample preparation and measurement procedure of FIG. 8 were used to measure and absorbance for the mixture.
- the mixture was transferred to a separatory funnel 804 for extraction with xylene 204 , and processed in a centrifuge 806 to remove impurities.
- the calibration solutions were used to find the calibration line where the coefficient of determination (r 2 ) was greater than 0.995.
- the absorbance curve for crude oil A shown in FIG. 6
- the absorbance curve for crude oil B shown in FIG. 7
- r 2 0.9963.
- Equation 1 C is the concentration of total crude oil in ppm, in is the mass of crude oil in mg, and V t is the total volume of the solution in L.
- y is the absorbance with an arbitrary unit (absorbance units), in is the slope of the calibration line, x is the concentration of total crude oil in ppm, and c is the y-intercept.
- Equation 2 The concentration of total crude oil extracted from the water sample was determined using external calibration by rearranging Equation 2 as follows:
- the concentration value that was calculated from the absorbance measured in the device is the amount of the extracted crude oil in the added xylene
- the concentration of total crude oil in water was determined by applying the following equation to account for LLE concentration change, according to Equations 4 and 5:
- Equations 4 and 5 C w is the concentration of total crude oil in water in ppm, V w is the volume of water in mL, C xyl is the concentration of total crude oil in the added xylene in ppm, and V xyl is the volume of the added xylene in mL.
- Equation 6 C k is the concentration of the QC sample, Cm is the mean of the actual concentration, t is the value of the tabulated t-test at (n ⁇ 1) replicates at 95% confidence interval, s is the estimated standard deviation, and n is the number of replicates. The uncertainty is determined using Equation 7:
- the prepared quality control samples showed that the method has a relative error ⁇ 8.69%.
- the method had repeatability expressed as relative standard deviation with the value of ⁇ 1.9%.
- the method had relative uncertainty equal to ⁇ 0.0137.
- An embodiment described in examples herein provides a method for quantifying a crude oil in water.
- the method includes selecting an ultraviolet/visible (UV/Vis) wavelength to perform a measurement, preparing calibration solutions in xylene, and preparing a calibration curve from the calibration solutions.
- a sample is prepared including extracting the crude oil from the water in a ⁇ separation with xylene.
- An absorbance of the sample in the xylene is measured at the UV/Vis wavelength.
- a concentration of the crude oil in the water is calculated from the absorbance.
- selecting the UV/Vis wavelength includes dissolving a 100 ppm sample of the crude oil in xylene to form a test solution, measuring a UV/Vis absorbance spectrum of the test solution, and selecting a wavelength in the UV/Vis absorbance spectrum at or near a maximum absorbance.
- preparing the calibration solutions includes preparing a series of crude oil solutions in xylene at concentrations between about 10 ppm and about 1000 ppm.
- preparing the calibration curve includes obtaining three measurements of an absorbance of each calibration solution in the series of crude oil samples at the UV/Vis wavelength, averaging the three measurements of each calibration solution to obtain an average absorbance value for that calibration solution, plotting the average absorbance value for each calibration solution against the concentration of that calibration solution, and performing a linear regression to obtain a calibration equation.
- the method includes determining that the coefficient of determination (r 2 ) of the calibration equation is at least 0.995.
- preparing the sample includes adding a water sample to a separatory funnel, adding the xylene to the separatory funnel, shaking the separatory funnel, extracting a xylene layer, and centrifuging the xylene layer.
- measuring the absorbance includes placing the xylene layer in a cuvette after centrifugation, obtaining three measurements of the absorbance of the xylene layer, and calculating the concentration of crude oil in the xylene layer.
- calculating the concentration of the crude oil in the water by normalizing the concentration of the crude oil in the xylene layer by the volume of the xylene versus the volume of the water, using the equation:
- C w is the concentration of total crude oil in water in ppm
- V w is the volume of water in mL
- C xyl is the concentration of total crude oil in the added xylene in ppm
- V xyl is the volume of the added xylene in mL.
- the method includes preparing quality control samples by preparing a synthetic brine and mixing a known amount of the crude oil with the synthetic brine.
- the method includes measuring the amount of the crude oil in the synthetic brine by extracting the crude oil from the synthetic brine using xylene in a liquid-liquid extraction, removing a xylene layer from the liquid-liquid extraction, centrifuging the xylene layer, measuring the absorbance of the xylene layer, and calculating the concentration of the crude oil in the synthetic brine from the absorbance of the xylene layer.
- the method includes repeating the measurement of the concentration of the crude oil in the synthetic brine for 10 measurements, and determining an error for the measurement.
Abstract
A method for quantifying a crude oil in water is provided. The method includes selecting an ultraviolet/visible (UV/Vis) wavelength to perform a measurement, preparing calibration solutions in xylene, and preparing a calibration curve from the calibration solutions. A sample is prepared including extracting the crude oil from the water in a two-phase separation with xylene. An absorbance of the sample in the xylene is measured at the UV/Vis wavelength. A concentration of the crude oil in the water is calculated from the absorbance.
Description
- The present disclosure is directed to a method for the quantitative determination of total crude oil in water by absorbance spectrophotometry.
- The production of crude oil often produces entrained water, termed a water-cut. As reservoirs age, the water-cut increases. Generally, the entrained water is separated from the oil, and treated in a water oil separation plant (WOSP) to separate dispersed oily materials (emulsified oil) from the produced water, so that it may be injected into disposal wells or used for other applications. The basic design of the WOSP was intended to handle water-cuts less than 10%.
- However, as an oil field matures, oil production decreases while water production increases. The current water/oil ratio is estimated at 2:1 to 3:1 worldwide, converting to a water cut of 50% to 75% of the total amount of produced fluids. A higher water-cut causes a significant reduction of separation efficiency, as the water requires more retention time in a WSOP for complete separation. An extreme volume of emulsified water can exceed the processing capacity of the WSOP, resulting in incomplete oil water separation. This leads to poor quality, or offspec, water being provided to injection wells. Accordingly, determining the amount of oil in wastewater streams is important for determining the operations needed for purification prior to disposal.
- An embodiment described in examples herein provides a method for quantifying a crude oil in water. The method includes selecting a ultraviolet/visible (UV/Vis) wavelength to perform a measurement, preparing calibration solutions in xylene, and preparing a calibration curve from the calibration solutions. A sample is prepared including extracting the crude oil from the water in a two-phase separation with xylene. An absorbance of the sample in the xylene is measured at the UV/Vis wavelength. A concentration of the crude oil in the water is calculated from the absorbance.
-
FIG. 1 is a process flow diagram of a method for determining total crude oil in water by absorbance spectroscopy spectrophotometry. -
FIG. 2 is a schematic diagram of the wavelength selection process. -
FIG. 3 is a polynomial interpolation of absorbance for a 100 ppm solution of a first crude oil in xylene. -
FIG. 4 is a polynomial interpolation of absorbance for a 100 ppm solution of a second crude oil in xylene. -
FIG. 5 is a schematic diagram of the calibration procedure. -
FIG. 6 is a plot of the calibration curve for the first crude oil. -
FIG. 7 is a plot of the calibration curve for the second crude oil. -
FIG. 8 is a schematic diagram of the sample preparation and measurement procedure. - A method is provided for the quantitative determination of crude oil in water by UV-visible spectrophotometry. A corresponding crude oil sample is analyzed by the spectrophotometer at a range of wavelength values to determine the wavelength value that will be used in calibration and sample measurement. Then, an oil-soluble solvent, xylene, is introduced to the water samples for liquid-liquid extraction (LLE). The organic layer is then separated from water. The concentration of total crude oil in the organic layer is determined by external calibration in the ppm level using UV-Visible spectrophotometry at the chosen wavelength value. Subsequently, the concentration of total crude oil in water is calculated.
-
FIG. 1 is a process flow diagram of amethod 100 for determining total crude oil in water by absorbance spectroscopy spectrophotometry. Themethod 100 begins atblock 102 with selecting a wavelength in the UV-Visible spectrum for the measurement. As different crude oil samples have different compositions, selecting an appropriate wavelength will increase both the accuracy and the precision of the measurement. A corresponding crude oil sample is analyzed by the spectrophotometer at a range of wavelength values to determine the wavelength value that will be used in calibration and sample measurement. The selection of the wavelength is discussed further with respect toFIGS. 2-4 of the examples. - At
block 104, calibration solutions are mixed in xylene at a number of concentrations. The concentrations may be selected to cover the expected range of oil concentrations. Atblock 106, the calibration solutions are used to determine a calibration curve. The mixing of the calibration solutions and the determination of the calibration curve are discussed further with respect toFIGS. 5-7 of the examples. - At
block 108, the sample is prepared for measurement. An oil-soluble solvent, xylene, is introduced to the water samples for liquid-liquid extraction (LLE), for example, in a separatory funnel. The organic layer is then separated from water and centrifuged to remove solid impurities and water droplets. Atblock 110, the absorbance of the sample is measured at the selected wavelength. Atblock 112, the concentration of total crude oil in the organic layer is determined by from the calibration curves and the absorbance of the sample. The measurement of the absorbance of the sample and the calculation of the crude oil concentration are discussed further with respect toFIG. 8 of the example. - Instrumentation
- The
method 100 described herein uses the following equipment (or equivalent). Weights are measured on a calibrated analytical balance capable of weighing up to 0.1 mg, for example, a Mettler model AT-261 available from Mettler-Toledo of Columbus, Ohio, USA. The centrifuge used for the purification of the oil sample after extraction can be a Seta Oil Test Centrifuge 90000-0 (operating range: 300-2800 rpm) available from Stanhope-Seta of Chertsey, Surrey, UK. The spectrophotometer used for the UV-Vis measurements was a Jenway 6300 UV-Vis Spectrophotometer available from Cole-Panner of Stone, Staffordshire, UK. - Materials and Reagents
- Lab Equipment
- The lab equipment used for the
method 100 includes a 500 mL separatory funnel, 15 mL glass test tubes, 10 mL volumetric flasks, 50 mL volumetric flasks, adjustable volume pipettes, and a spectrophotometer cuvette. Disposable pipette tips were also used. As some measurements may be made in the ultraviolet range, the cuvette may be a 1 cm×1 cm quartz cuvette. - Chemicals
- The chemicals used in the
method 100 includes xylene, purity ≥98.5%, sodium chloride, purity ≥99.6%, and calcium chloride dihydrate, purity ≥99.0%. A corresponding crude oil sample from the same source of the crude oil in the water samples is used to select the measurement wavelength and prepare the calibration samples. In this example described herein, two crude oil samples were used to demonstrate the techniques, termed crude oil A and crude oil B, herein. - Select Wavelength for Measurement
-
FIG. 2 is a schematic diagram of the wavelength selection process. This may correspond to block 102 of themethod 100 ofFIG. 1 . InFIG. 2 , the correspondingcrude oil 202 and xylene tool for were combined to form thesolution 206 of crude oil in xylene. Thesolution 206 were measured in thespectrophotometer 208 to generate a number of values of absorbance at different wavelengths. In some embodiments, a scanning spectrophotometer may be used to generate a spectrum. - The spectrophotometer was powered and allowed to warm until the absorbance (or any other reading, such as % T or CONC) reading was stable.
- As described above, the corresponding
crude oil 202 was taken from the same source of crude oil as would be present in the water samples. 0.001 g of the corresponding crude oil was added to in a 10 mL volumetric flask and diluted to the mark with xylene. The flask was shaken to prepare a 100 ppm solution (other concentrations can be used). - ABS (absorbance) was selected from the control panel of the device.
- Xylene was added to the cuvette and the outside walls of the cuvette were cleaned with a tissue paper, then placed in the spectrophotometer 208 (rinsing the cuvette walls was performed). The xylene measurement was used as the blank. A wavelength value was selected and the calibrate operation was selected. Blank calibrations were performed for each selected wavelength.
- The cuvette was filled with the prepared crude oil solution and placed in the
spectrophotometer 208 after the outside of the cuvette was rinsed. The absorbance was recorded, and the measurements were repeated at different wavelengths to cover the range of 320-1000 nm. - A wavelength value was selected to have high relative absorbance. This will result in an external calibration line with a good repeatability, r2>0.995, and substantially low percentage error, <10%. For example, 450 nm was chosen for crude oil A, which is near to the maximum absorbance wavelength, while 350 nm was chosen for crude oil B, which is the maximum absorbance wavelength. This is shown in
FIGS. 3 and 4 .FIG. 3 is a polynomial interpolation of absorbance for a 100 ppm solution of a first crude oil in xylene.FIG. 4 is a polynomial interpolation of absorbance for a 100 ppm solution of a second crude oil in xylene. - Calibration and measurement at 450 nm for crude oil A resulted in an r2=1 and a % error of less than about −8.69%, while calibration and measurement at 350 nm for crude oil B resulted in an r2=0.9963 and a % error of less than about −3.22%. The calibration curves are described further below.
- Determine Calibration Curve
-
FIG. 5 is a schematic diagram of the calibration procedure. This may correspond toblocks FIG. 1 . Like numbered items are as described with respect toFIG. 2 . InFIG. 5 , the correspondingcrude oil 202 was mixed withxylene 204 to form a series of calibration solutions, for example, at 10ppm 502, 20ppm 504, 40ppm 506, 60ppm 508, 80ppm ppm ppm ppm ppm ppm ppm 522, among others. For example, 0.0001 g of the corresponding crude oil was added to a 10 mL volumetric flask and diluted to the mark with xylene. The flask was then shaken to prepare a 10 ppm solution (add 0.0002 g of crude oil instead of 0.0001 g for 20 ppm . . . etc.). - The specific concentration selected may depend on the expected concentration of the crude oil in water. The absorbance of each of the calibration solutions 502-522 are then measured at the selected wavelength in the
spectrophotometer 208 as described with respect to the wavelength selection process. The calculations used to determine the concentrations are described below. - For example, a cuvette with xylene was placed in the instrument and the calibrate button was pressed. The cuvette was then filled with a prepared crude oil calibration solution and placed in the spectrophotometer (rinsing is recommended).
- The absorbance of the solution was measured (3 repeated measurements for each calibration solution) and the results were recorded. The absorbance of the blank was checked after every 6 to 9 measurements to ensure it was at zero. The calibration results for the first crude oil sample (A) are shown in Table 1.
-
TABLE 1 Typical calibration measurements of crude oil A in xylene solutions. Tube Concentration Absorbance at 450 nm No. (mg/L) Trial 1Trial 2Trial 3 Average 0 0.00 0.000 0.000 0.000 0.0000 1 10.10 0.005 0.006 0.005 0.0053 2 21.31 0.011 0.011 0.009 0.0103 3 45.37 0.022 0.021 0.021 0.0213 4 68.15 0.032 0.032 0.032 0.0320 5 93.66 0.046 0.044 0.044 0.0447 6 131.75 0.062 0.061 0.061 0.0613 7 269.13 0.125 0.124 0.126 0.1250 8 534.79 0.244 0.244 0.245 0.2443 9 799.91 0.370 0.369 0.370 0.3697 10 972.11 0.452 0.451 0.451 0.4513 11 1010.68 0.466 0.467 0.465 0.4660 - The measured absorbances were plotted versus the concentrations, and a calibration line was constructed to find the equation of the line as shown in
FIGS. 6 and 7.FIG. 6 is a plot of the calibration curve for the first crude oil.FIG. 7 is a plot of the calibration curve for the second crude oil. For both crude oils, it was confirmed that the r2 is 0.995 or higher. - Sample Preparation and Measurement
-
FIG. 8 is a schematic diagram of the sample preparation and measurement procedure. This corresponds toblocks FIG. 1 . Like numbered items are as described with respect toFIG. 2 . After calibration, awater sample 802 was collected in a water sample bottle. The water sample bottle, including thewater sample 802, was weighed and the total mass of the bottle was recorded. Thewater sample 802 was transferred to aseparatory funnel 804 and the mass of the empty bottle was recorded to determine the mass of thewater sample 802. - An appropriate amount of
xylene 204 was added to theseparatory funnel 804 and the amount of the addedxylene 204 was recorded. Generally, the volume of the addedxylene 204 depends on the amount of crude oil present in the water sample. However, the volume of the addedxylene 204 generally equals about 10 vol. % to about 34 vol. % of thewater sample 802. - The
separatory funnel 804 was vigorously shaken, and the bottom, or water, layer was discarded. The top, or xylene, layer was transferred to a test tube. In some cases, the solution is diluted with additional xylene if the expected concentration is outside of the calibration range. - The test tube was placed in a
centrifuge 806, and centrifuged for 5 minutes at 1500 rpm to remove water droplets and solids in the xylene layer. A pipet was used to transfer the xylene layer to the cuvette, avoiding the bottom of the test tube and the wall of the test tube, as the centrifugation pushed the water and solids down or to the side. - The cuvette was placed in the
spectrophotometer 208, and the absorbance of the separated xylene layer was measured at the same wavelength used in the calibration. Three repeated measurements were run for each sample, and an average was calculated. - The concentration of total crude oil was then calculated from the recorded measurements using the equation shown in the calculation section below. Tables 2 and 3 show typical values and results for a sample of crude oil A in water.
-
TABLE 2 Typical absorbance and concentration values of the separated xylene layer and the mass and volume of water in the water samples. Con. of total Mass of Mass of Absorbance values at 450 nm crude oil in full empty Mass of Volume of of the separated xylene layer xylene layer bottle, mf bottle, me water, mw (g) = water (mL) = Name Trial 1 Trial 2Trial 3 Average (mg/L) (g) (g) mf − me density/mw Sample 1 0.085 0.084 0.085 0.08467 168.54 571.4 243.2 328.2 328.851 Sample 20.165 0.167 0.166 0.16600 331.20 568.1 243.2 324.9 325.545 -
TABLE 3 Typical total crude oil A concentrations in water and the mass and volume of the added xylene. Concentration Mass of xylene, Volume of xylene of total crude oil A Name mxyl (g) (mL) = density/mxyl in water (mg/L) Sample 124.900 28.953 14.84 Sample 230.200 35.116 35.73 - Quality control samples were prepared to determine the accuracy and precision of the method. To prepare the samples, 1 g of sodium chloride was added to a 50 mL volumetric flask and diluted to the mark with distilled water. The solution was shaken vigorously, resulting in a 2 wt. % NaCl solution (mass percentage).
- 3.749 g of calcium chloride dihydrate was added to a 50 mL volumetric flask, diluted to the mark with distilled water, and shaken vigorously. This prepared a 6 wt. % CaCl2 solution (mass percentage).
- The two prepared solutions were mixed, to prepare 100 mL of a 1 wt. % NaCl, 3 wt. % CaCl2) brine solution. 0.001 g of the corresponding crude oil was added to a 10 mL volumetric flask, and diluted with the prepared brine to the mark and shaken. This prepared a 100 ppm mixture for the tests, although any concentration in the calibration range 10-1000 ppm can be used.
- The sample preparation and measurement procedure of
FIG. 8 were used to measure and absorbance for the mixture. For example, the mixture was transferred to aseparatory funnel 804 for extraction withxylene 204, and processed in acentrifuge 806 to remove impurities. - Evaluation of Quality Control Data
- Quality Control (QC)
- QC samples are crude oil in brine mixtures that are treated as the samples. Using 3 QC samples of crude oil A in water containing 121.82 ppm, 422.76 ppm, and 890.28 ppm respectively, the relative error and the relative standard deviation for 10 replicate measurements of each (n=10) were found to be less than or equal to about −8.69% and less than or equal to about 1.9%, respectively.
- Evaluation of Linearity
- In addition to being used for the quantification, the calibration solutions were used to find the calibration line where the coefficient of determination (r2) was greater than 0.995. As described herein, the absorbance curve for crude oil A, shown in
FIG. 6 , is linear in the provided range of concentrations (10-1000) with an r2 of 1. Similarly, the absorbance curve for crude oil B, shown inFIG. 7 , is linear with r2=0.9963. - Calculations
- Concentrations of the Calibration Solutions
-
- the total crude oil concentration of each solution was determined using
Equation 1 as follows:
- the total crude oil concentration of each solution was determined using
-
- In
Equation 1, C is the concentration of total crude oil in ppm, in is the mass of crude oil in mg, and Vt is the total volume of the solution in L. - Calibration
- The correlation between absorbance and the concentration of total crude oil was determined by linear regression from the external calibration samples, using Equation 2:
-
y=mx+c Equation 2 - In
equation 2, y is the absorbance with an arbitrary unit (absorbance units), in is the slope of the calibration line, x is the concentration of total crude oil in ppm, and c is the y-intercept. - Concentrations of the Samples
- The concentration of total crude oil extracted from the water sample was determined using external calibration by rearranging
Equation 2 as follows: -
- Since the concentration value that was calculated from the absorbance measured in the device is the amount of the extracted crude oil in the added xylene, the concentration of total crude oil in water was determined by applying the following equation to account for LLE concentration change, according to Equations 4 and 5:
-
- In Equations 4 and 5, Cw is the concentration of total crude oil in water in ppm, Vw is the volume of water in mL, Cxyl is the concentration of total crude oil in the added xylene in ppm, and Vxyl is the volume of the added xylene in mL.
- To calculate the concentration of a calibration solution given that: the mass of crude oil (m)=0.0001 g and the total volume (Vt)=10 mL. Using
Equation 1, the concentration of total crude oil (C) is determined as follows: -
- To calculate the concentration of total crude oil in the added xylene given that (from Table 2) the average absorbance (y)=0.08467, and (from
FIG. 6 ), m=0.0005 and c=0.0004. Using Equation 3, the concentration of total crude oil in the added xylene (x) is determine as follows: -
- To calculate the concentration of total crude oil in water given that the concentration of total crude oil in added xylene (Cxyl)=168.54 ppm, (from Table 3) the volume of added xylene (Vxyl)=28.953 mL, and (from Table 2) the volume of water (Vw)=328.851 mL. Using Equation 5, the concentration of total crude oil in water (Ce) is determine as follows:
-
- Performance Characteristics
- The repeatability of the measurement expressed in relative standard deviation was determined by 10 replicate measurements (n=10) of a QC sample of 121.82 ppm. The relative standard deviation was <1.9%.
- The measurement's uncertainty was determined based on 10 replicate measurements (n=10) of the QC sample using the following equation:
-
- In Equation 6, Ck is the concentration of the QC sample, Cm is the mean of the actual concentration, t is the value of the tabulated t-test at (n−1) replicates at 95% confidence interval, s is the estimated standard deviation, and n is the number of replicates. The uncertainty is determined using Equation 7:
-
- The relative uncertainty was found to be ±0.0137, and the relative error and relative standard deviation were reported as described with respect to the quality control data.
- Reporting of Results
- An average of three measurement for the concentration of total crude oil in water were reported in parts per million (mg/L) up to two decimal points. The coefficients of determination (r2) for multiple trials of calibrations were high, ranging from 0.999 to 1, indicating a high correlation between the response and the concentrations of the prepared solutions.
- The prepared quality control samples showed that the method has a relative error ≤−8.69%. The method had repeatability expressed as relative standard deviation with the value of ≤1.9%. The method had relative uncertainty equal to ±0.0137.
- An embodiment described in examples herein provides a method for quantifying a crude oil in water. The method includes selecting an ultraviolet/visible (UV/Vis) wavelength to perform a measurement, preparing calibration solutions in xylene, and preparing a calibration curve from the calibration solutions. A sample is prepared including extracting the crude oil from the water in a \ separation with xylene. An absorbance of the sample in the xylene is measured at the UV/Vis wavelength. A concentration of the crude oil in the water is calculated from the absorbance.
- In an aspect, selecting the UV/Vis wavelength includes dissolving a 100 ppm sample of the crude oil in xylene to form a test solution, measuring a UV/Vis absorbance spectrum of the test solution, and selecting a wavelength in the UV/Vis absorbance spectrum at or near a maximum absorbance.
- In an aspect, preparing the calibration solutions includes preparing a series of crude oil solutions in xylene at concentrations between about 10 ppm and about 1000 ppm. In an aspect, preparing the calibration curve includes obtaining three measurements of an absorbance of each calibration solution in the series of crude oil samples at the UV/Vis wavelength, averaging the three measurements of each calibration solution to obtain an average absorbance value for that calibration solution, plotting the average absorbance value for each calibration solution against the concentration of that calibration solution, and performing a linear regression to obtain a calibration equation. In an aspect, the method includes determining that the coefficient of determination (r 2) of the calibration equation is at least 0.995.
- In an aspect, preparing the sample includes adding a water sample to a separatory funnel, adding the xylene to the separatory funnel, shaking the separatory funnel, extracting a xylene layer, and centrifuging the xylene layer.
- In an aspect, measuring the absorbance includes placing the xylene layer in a cuvette after centrifugation, obtaining three measurements of the absorbance of the xylene layer, and calculating the concentration of crude oil in the xylene layer.
- In an aspect, calculating the concentration of the crude oil in the water by normalizing the concentration of the crude oil in the xylene layer by the volume of the xylene versus the volume of the water, using the equation:
-
- wherein Cw is the concentration of total crude oil in water in ppm, Vw is the volume of water in mL, Cxyl is the concentration of total crude oil in the added xylene in ppm, and Vxyl is the volume of the added xylene in mL.
- In an aspect, the method includes preparing quality control samples by preparing a synthetic brine and mixing a known amount of the crude oil with the synthetic brine. In an aspect, the method includes measuring the amount of the crude oil in the synthetic brine by extracting the crude oil from the synthetic brine using xylene in a liquid-liquid extraction, removing a xylene layer from the liquid-liquid extraction, centrifuging the xylene layer, measuring the absorbance of the xylene layer, and calculating the concentration of the crude oil in the synthetic brine from the absorbance of the xylene layer. In an aspect, the method includes repeating the measurement of the concentration of the crude oil in the synthetic brine for 10 measurements, and determining an error for the measurement.
- Other implementations are also within the scope of the following claims.
Claims (11)
1. A method for quantifying a crude oil in water, comprising:
selecting an ultraviolet/visible (UV/Vis) wavelength to perform a measurement;
preparing calibration solutions in xylene;
preparing a calibration curve from the calibration solutions;
preparing a sample comprising extracting the crude oil from the water in a two-phase separation with xylene;
measuring an absorbance of the sample in the xylene at the UV/Vis wavelength; and
calculating a concentration of the crude oil in the water from the absorbance.
2. The method of claim 1 , wherein selecting the UV/Vis wavelength comprises:
dissolving a 100 ppm sample of the crude oil in xylene to form a test solution;
measuring a UV/Vis absorbance spectrum of the test solution; and
selecting a wavelength in the UV/Vis absorbance spectrum at or near a maximum absorbance.
3. The method of claim 1 , wherein preparing the calibration solutions comprises preparing a series of crude oil solutions in xylene at concentrations between about 10 ppm and about 1000 ppm.
4. The method of claim 3 , wherein preparing the calibration curve comprises:
obtaining three measurements of an absorbance of each calibration solution in the series of crude oil samples at the UV/Vis wavelength;
averaging the three measurements of each calibration solution to obtain an average absorbance value for that calibration solution;
plotting the average absorbance value for each calibration solution against the concentration of that calibration solution; and
performing a linear regression to obtain a calibration equation.
5. The method of claim 4 , comprising determining that the coefficient of determination (r2) of the calibration equation is at least 0.995.
6. The method of claim 1 , wherein preparing the sample comprises:
adding a water sample to a separatory funnel;
adding the xylene to the separatory funnel;
shaking the separatory funnel;
extracting a xylene layer; and
centrifuging the xylene layer.
7. The method of claim 6 , wherein measuring the absorbance comprises:
placing the xylene layer in a cuvette after centrifugation;
obtaining three measurements of the absorbance of the xylene layer; and
calculating the concentration of crude oil in the xylene layer.
8. The method of claim 7 , comprising calculating the concentration of the crude oil in the water by normalizing the concentration of the crude oil in the xylene layer by the volume of the xylene versus the volume of the water, using the equation:
wherein Cw, is the concentration of total crude oil in water in ppm, Vw is the volume of water in mL, Cxy1 is the concentration of total crude oil in the added xylene in ppm, and Vxy1 is the volume of the added xylene in mL.
9. The method of claim 1 , comprising preparing quality control samples by:
preparing a synthetic brine; and
mixing a known amount of the crude oil with the synthetic brine.
10. The method of claim 9 , comprising measuring the amount of the crude oil in the synthetic brine by:
extracting the crude oil from the synthetic brine using xylene in a liquid-liquid extraction;
removing a xylene layer from the liquid-liquid extraction;
centrifuging the xylene layer;
measuring the absorbance of the xylene layer; and
calculating the concentration of the crude oil in the synthetic brine from the absorbance of the xylene layer.
11. The method of claim 10 , comprising;
repeating the measurement of the concentration of the crude oil in the synthetic brine for 10 measurements; and
determining an error for the measurement.
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Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110151576A1 (en) * | 2008-07-18 | 2011-06-23 | Lux Innovate Limited | Method to assess multiphase fluid compositions |
US20120170023A1 (en) * | 2011-01-04 | 2012-07-05 | Exxonmobil Research And Engineering Company | Method and Apparatus for a Mid-Infrared (MIR) System for Real Time Detection of Petroleum in Colloidal Suspensions of Sediments and Drilling Muds During Drilling Operations, Logging and Production Operations |
US20130124106A1 (en) * | 2011-11-11 | 2013-05-16 | Chevron U.S.A. Inc. | Method for estimating sediment content of a hydroprocessed hydrocarbon-containing feedstock |
US20200033315A1 (en) * | 2018-07-27 | 2020-01-30 | Exxonmobil Research And Engineering Company | Methods for determining residual surfactant concentrations in oil and water phases |
US20210102932A1 (en) * | 2019-10-04 | 2021-04-08 | Conocophillips Company | Elemental sulfur analysis in fluids |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5381002A (en) | 1992-11-27 | 1995-01-10 | Texaco Inc. | Fluorescence method of quantifying hydrocarbons, including crude oil, dispersed in water |
US6117682A (en) | 1993-04-27 | 2000-09-12 | Dexsil Corporation | Method for detecting hydrocarbons in water |
US20100231904A1 (en) | 2009-03-12 | 2010-09-16 | Tyrie Colin C | Method and Device for Measuring Hydrocarbons in Aqueous Solutions |
US20140264096A1 (en) | 2013-03-15 | 2014-09-18 | Dale Brost | Multi-axis optical measurement of fluid streams with sonic cleaning and homogenization |
US9297747B2 (en) | 2013-07-18 | 2016-03-29 | Saudi Arabian Oil Company | Method to determine trace amounts of crude oil by spectroscopic absorption |
-
2022
- 2022-02-28 US US17/682,243 patent/US11726033B1/en active Active
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110151576A1 (en) * | 2008-07-18 | 2011-06-23 | Lux Innovate Limited | Method to assess multiphase fluid compositions |
US20120170023A1 (en) * | 2011-01-04 | 2012-07-05 | Exxonmobil Research And Engineering Company | Method and Apparatus for a Mid-Infrared (MIR) System for Real Time Detection of Petroleum in Colloidal Suspensions of Sediments and Drilling Muds During Drilling Operations, Logging and Production Operations |
US20130124106A1 (en) * | 2011-11-11 | 2013-05-16 | Chevron U.S.A. Inc. | Method for estimating sediment content of a hydroprocessed hydrocarbon-containing feedstock |
US20200033315A1 (en) * | 2018-07-27 | 2020-01-30 | Exxonmobil Research And Engineering Company | Methods for determining residual surfactant concentrations in oil and water phases |
US20210102932A1 (en) * | 2019-10-04 | 2021-04-08 | Conocophillips Company | Elemental sulfur analysis in fluids |
Non-Patent Citations (1)
Title |
---|
Leong et al., "UV-Vis Spectroscopy: A new approach for assessing the color index of transformer insulating oil," Sensors, Vol 18, No. 2175, 15 pages. (Year: 2018) * |
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