Application of In Situ ATR-FTIR Sресtrоsсору for Determination of Wax Aрреаrаnсе Tеmреrаturе at High-Prеssurе СО2 Conditions

Shalygin, A. S.; Morozov, Evgeny V.; Martyanov, Oleg N.

doi:10.1134/s0965544122100176

Cited by 1 publication

(6 citation statements)

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“…The intensity of the CO 2 bands increases with increased pressure, while the intensity of waxy crude oil bands decreases, which is associated with CO 2 sorption and, accordingly, waxy crude oil swelling. The values of the wavenumbers for the CO 2 bands do not differ from those observed in the paraffin wax solution, 46 polyethylene, 54 and crude oil. 44 The absence of additional bands in ATR FT-IR spectra indicates that CO 2 does not interact with the components of the waxy crude oil studied.…”

Section: Resultsmentioning

confidence: 60%

“…Wax Appearance Temperature (WAT) Determination in Waxy Crude Oil at Ambient Conditions In our recent work, it was proposed to use the high-pressure ATR FT-IR method to determine the WAT of a model solution of paraffin wax under high CO 2 pressure. 46 In this work, high-pressure ATR FT-IR was applied to determine the WAT of waxy crude oil under the pressure of gases such as CO 2 , natural gas, and N 2 . Note that the content of C 17 -C 35 waxes in the studied waxy crude oil and model solution is 11.12 and 10 wt%, respectively, which is close enough for comparison, but the molecular composition of oil waxes has a maximum at C 20, and a wider distribution of carbon content compared to paraffin wax (maximum at C 24 -C 25 ) 46 (Figure S1, Supplemental Material).…”

Section: Resultsmentioning

confidence: 99%

“…46 In this work, high-pressure ATR FT-IR was applied to determine the WAT of waxy crude oil under the pressure of gases such as CO 2 , natural gas, and N 2 . Note that the content of C 17 –C 35 waxes in the studied waxy crude oil and model solution is 11.12 and 10 wt%, respectively, which is close enough for comparison, but the molecular composition of oil waxes has a maximum at C 20, and a wider distribution of carbon content compared to paraffin wax (maximum at C 24 –C 25 ) 46 (Figure S1, Supplemental Material).…”

Section: Resultsmentioning

confidence: 99%

“…Equipment for the determination of waxy crude oil WAT using ATR FT-IR is described in the work. 46 The ATR FT-IR spectra were obtained using a Bruker Vertex 70 V FT-IR spectrometer with a mercury–cadmium–tellurium single-element detector, utilizing a diamond ATR accessory (Golden Gate, Specac) with USB temperature controller with accuracy to ±0.1 °C. Gases were introduced and regulated using a syringe pump (Teledyne ISCO D260).…”

Section: Methodsmentioning

confidence: 99%

“…45 We recently demonstrated an ability to measure the WAT of model paraffin solution under CO 2 high-pressure by in situ ATR FT-IR. 46 The effectiveness of this method for determining WAT and the possibility of obtaining information about the spectral characteristics of all components under given conditions was demonstrated.…”

Section: Introductionmentioning

confidence: 99%

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Features of Wax Appearance Temperature Determination of Waxy Crude Oil Using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy Under Ambient and High Pressure

Shalygin,

Kozhevnikov,

Morozov

et al. 2023

Appl Spectrosc

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The wax appearance temperature (WAT), being one of the key characteristics of waxy crude oil and other waxy substances, is used for the necessary assessment of the phase stability of materials during various technological processes. However, the determination of this parameter as well as peculiarities of wax formation under high gas pressure suffers from the lack of suitable techniques for this task. To address this issue, an attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) method has been applied for the first time to measure the WAT of waxy crude oil under high gas pressure. Carbon dioxide (CO2), nitrogen, and natural gas were used in the study due to their widespread applicability as injection gases in enhanced oil recovery methods. The S2/S1 versus temperature method based on changes in the band of rocking vibrations of the CH2 group was applied to determine WAT. It was found that the ATR FT-IR method based on the proposed dependence S2/S1 versus temperature gives lower WAT values compared to those observed by viscometry, magnetic resonance imaging inspection, and cross-polarized microscopy methods for the waxy crude oil studied. A detailed analysis was carried out using variable-temperature ATR FT-IR spectra of waxy crude oil in the temperature region near the WAT. Essentially different dynamics of wax crystal formation in waxy oil sample and model paraffin solution were demonstrated during the cooling process. The results obtained by high-pressure ATR FT-IR showed that CO2 and natural gas reduce the WAT, while nitrogen has virtually no effect. In addition, for the studied oil, it was found that high pressure of CO2 and natural gases leads to a visual decrease in the amount of wax crystals precipitated, but not to the complete disappearance of microcrystals at a certain temperature and pressure. The results obtained proved that ATR FT-IR can be an effective method for proper determinations of WAT under high-pressure conditions similar to those met in practice.

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Section: Resultsmentioning

confidence: 60%

Section: Resultsmentioning

confidence: 99%