In situ Raman spectroscopic quantification of CH4–CO2 mixture: application to fluid inclusions hosted in quartz veins from the Longmaxi Formation shales in Sichuan Basin, southwestern China

Qiu, Ye; Wang, Xiaolin; Liu, Xian; Cao, Jian; Yifeng, Liu; Xi, Binbin; Gao, Wanlu

doi:10.1007/s12182-019-00395-z

Cited by 16 publications

(25 citation statements)

References 64 publications

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“…However, this effect is not so pronounced for the ν 1 band, since the processes of collisional line mixing dominate here [ 26 ]. The ν 1 peak shifts to the region of low wavenumbers as the pressure increases, which corresponds to the data of [ 22 , 27 , 28 , 49 , 50 ]. The effect of the N 2 and CO 2 environments leads to different broadening and shifts of the CH 4 lines.…”

Section: Resultssupporting

confidence: 82%

Depolarization Ratio of the ν1 Raman Band of Pure CH4 and Perturbed by N2 and CO2

Tanichev

Petrov

2021

Molecules

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In this work, the effect of nitrogen and carbon dioxide on the depolarization ratio of the ν1 band of methane in the pressure range of 0.1–5 MPa is studied. A high-sensitivity single-pass Raman spectrometer was used to obtain accurate results. Moreover, we took into account the overlap of the ν1 band by the ν3 and ν2 + ν4 bands using the simulation of their spectra. The depolarization ratio of the ν1 band in pure methane is within 0–0.001, and the effect of nitrogen and carbon dioxide on this parameter is negligible in the indicated pressure range. The obtained results are useful for correct simulation of the Raman spectrum of methane at different pressures, which is necessary to improve the accuracy of gas analysis methods using Raman spectroscopy.

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Section: Resultssupporting

confidence: 82%

Depolarization Ratio of the ν1 Raman Band of Pure CH4 and Perturbed by N2 and CO2

Tanichev

Petrov

2021

Molecules

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“…One end of the silica capillary tube was connected to the syringe and was attached with AB glue. Then we cleaned the thinner tube with ethanol and inserted the tube slowly into the bottom of the FSCC's sealed end (Wang et al, 2011;Wang et al, 2020aWang et al, , 2020bQiu et al, 2020). The syringe was then used to draw a certain amount of the nC 16 H 34 and water solution and inject it into the FSCCs.…”

Section: Sample Preparation and Thermal Simulationmentioning

confidence: 99%

“…However, the fluid pressure changes in the FSCCs and the reactivity of SiO 2 have to be considered before FSCCs are used as reactors for chemical reactions (Chou et al, 2008;. Specifically, the pressure in the FSCCs can be monitored accurately during the experiment by connecting one end to a pressure transducer (Wang et al, 2011;Wang et al, 2020aWang et al, , 2020bQiu et al, 2020;. Pressure measurements methods for FSCCs with two sealed ends have to be investigated, especially for partial pressure changes of gaseous products.…”

Section: Geological Implications Of the Experimentsmentioning

confidence: 99%

“…Due to the development of visual experimental methods and technological progress of in situ spectroscopic analysis methods (laser Raman spectroscopy, fluorescence spectroscopy, infrared spectroscopy, X-ray diffraction analysis, etc. ), fused silica capillary capsules (FSCCs) have become essential for the study of fluid inclusions and fluid-rock interactions under high temperature and high pressure (Chou et al, 2008;Wang et al, 2011;Ni et al, 2011;Bourdet et al, 2014;Xu and Chou, 2017;Wang et al, 2018;Qiu et al, 2020;Wang et al, 2020b;. For example, Xu and Chou (2017) con-ducted experiments to analyze propane cracking in the presence/absence of water using FSCCs at temperatures from 300 to 400°C.…”

Section: Introductionmentioning

confidence: 99%

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Interactions between hydrocarbon-bearing fluids and calcite in fused silica capillary capsules and geological implications for deeply-buried hydrocarbon reservoirs

Jin

Yuan

Cao

et al. 2021

Sci. China Earth Sci.

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During the burial processes of deep/ultra-deep hydrocarbon reservoirs, the interactions between hydrocarbon-bearing fluids and reservoirs significantly affect the quality evolution of hydrocarbons and reservoirs; thus, this topic requires further investigation. In this study, the continuous evolution and the coupling mechanisms in various anhydrous and hydrous nC 16 H 34 -(water)-(calcite) systems in fused silica capillary capsules (FSCCs) were investigated using laser Raman spectroscopy, fluorescence color analysis, and fluorescence spectroscopy, and the mineral alterations were analyzed using scanning electron microscopy (SEM). The experimental results show that extensive organic-inorganic interactions occur in the systems if water is present, and different inorganic components have different effects on hydrocarbon degradation. Distilled water promotes freeradical thermal cracking and steps oxidation, forming more low-molecular-weight hydrocarbons, CO 2 , and organic acids (e.g., acetic acids) but suppresses the free-radical cross-linking, generating less high-molecular-weight hydrocarbons. However, in the presence of CaCl 2 water, the yields of hydrocarbon gases are lower than in the distilled water system because high concentrations of Ca ions inhibit the generation of free radicals. Calcites, which exhibit different surface reactivities in different fluid conditions, affect hydrocarbon degradation in different ways. In the anhydrous nC 16 H 34 -calcite system, calcites promote the generation of both hydrocarbon gases and high-molecular-weight hydrocarbons. In contrast, in the hydrous nC 16 H 34 -distilled (CaCl 2 ) watercalcite system, calcites promote the generation of hydrocarbon gases and suppress the generation of high-molecular-weight hydrocarbons. Calcite also reacts with organic acids via surface reactions to form secondary pores. Therefore, except for the formation temperature and pressure, organic-inorganic interactions are controlled by multiple factors, such as the water saturation, water type, water salinity, and the mineral content, resulting in different evolutions of the hydrocarbon degradation and reservoir properties.

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“…Spectral parameters (peak position, peak width, and peak intensity ratio) could be used to determine the pressure, density, and composition of the fluid in FIs. For instance, the concentration of dissolved CH 4 or CO 2 in water solution has been determined based on their peak area (or height) ratio [21][22][23][24][25], and the pressure (or density) of CH 4 can be determined by the peak position of the υ 1 band of CH 4 [17,[26][27][28][29][30][31][32][33]. In addition, the CO 2 density in FIs can be obtained by the measurements of the Fermi diad splitting of CO 2 [3,19,20,[33][34][35][36][37][38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Quantitative Raman Spectroscopic Determination of the Composition, Pressure, and Density of CO2-CH4 Gas Mixtures

Chen

Chou

2022

Journal of Spectroscopy

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The Raman spectra for pure CO2 and CH4 gases and their ten gas mixtures were collected at pressures and temperatures ranging from 2 MPa to 40 MPa and room temperature (∼24°C) to 300°C, respectively. A systematic analysis was carried out to establish a methodology for the quantitative determination of the composition, pressure, and density of CO2-CH4 mixtures. The shift in the peak position of the υ1 band for CH4 was sufficiently large to enable the accurate determination of the pressure of pure CH4 and CH4-dominated fluids (>50 mol% CH4). An equation representing the observed relationship of the peak position of the υ1 band of CH4, density, and composition was developed to calculate the density of CO2-CH4 mixtures. The Raman quantification factor F (CH4)/F (CO2) was demonstrated to be near a constant value of 5.048 ± 0.4 and was used to determine the CH4 to CO2 molar ratio in an unknown CO2-CH4‐bearing fluid with high internal pressure (>10 MPa) based on the Raman peak area ratio. The effect of temperature on the variation in Raman spectral parameters was also investigated at temperatures up to 300°C. The results showed that the effect of temperature must be considered when Raman spectral parameters are used to calculate the pressure, density, and composition of CO2-CH4 gas mixtures. Raman spectroscopic analysis results obtained for six samples prepared in fused silica capillary capsules were validated by comparison with the results obtained from microthermometry measurements.

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In situ Raman spectroscopic quantification of CH4–CO2 mixture: application to fluid inclusions hosted in quartz veins from the Longmaxi Formation shales in Sichuan Basin, southwestern China

Cited by 16 publications

References 64 publications

Depolarization Ratio of the ν1 Raman Band of Pure CH4 and Perturbed by N2 and CO2

Depolarization Ratio of the ν1 Raman Band of Pure CH4 and Perturbed by N2 and CO2

Interactions between hydrocarbon-bearing fluids and calcite in fused silica capillary capsules and geological implications for deeply-buried hydrocarbon reservoirs

Quantitative Raman Spectroscopic Determination of the Composition, Pressure, and Density of CO2-CH4 Gas Mixtures

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