Measurements of position-specific carbon isotopic compositions in propane by on-line Gas Chromatography-Pyrolysis-Gas Chromatography-Isotope Ratio Mass Spectrometer (GC-Py-GC-IRMS) and its preliminary application
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摘要: 遵循富集、色谱分离、瞬时裂解、同位素比值测试原则,搭建了气相色谱—裂解—气相色谱同位素比值质谱(GC-Py-GC-IRMS)在线位碳同位素测试系统用以测定特定化合物位碳同位素组成。由于丙烷瞬时裂解严格受控于动力学过程,因此,以丙烷为例,考察不同温度下丙烷裂解转化率以及裂解产物碳同位素组成,获得该测试系统丙烷的最佳裂解温度为780~820 ℃,并根据丙烷裂解动力学分馏模型,计算获得丙烷位碳同位素组成。对鄂尔多斯盆地大牛地气田已知上古生界煤系成因两件天然气样品丙烷位碳同位素进行了测定,结果表明,奥陶系马家沟组五段气藏和石炭—二叠系气藏天然气丙烷中心碳相同的碳同位素组成可能指示二者具有相同的气源,而石炭—二叠系气藏天然气丙烷端元碳同位素显著富集13C,则指示了其高演化阶段成因特征。研究成果初步展示了丙烷位碳同位素组成在天然气成因研究中具有广阔应用前景。Abstract: In this study, an on-line Gas Chromatography-Pyrolysis-Gas Chromatography-Isotope Ratio Mass Spectrometer (GC-Py-GC-IRMS) was established to conduct position-specific isotope analysis (PSIA) by enrichment of compound interested, chromatographic separation, instantaneous pyrolysis and isotope ratio measurement. Propane, as its instantaneous pyrolysis can be kinetically controlled, was selected for tests. The molar conversion (mol%) of propane during pyrolysis and the carbon isotopic compositions of pyrolysis products upon temperature sequence show that the optimal pyrolysis temperature of propane is 780-820 ℃ for its position-specific carbon isotope analysis. Integrated with carbon isotopic fractionation during the propane pyrolysis, the carbon isotopes of central and terminal carbon were successfully calculated. Two natural gas samples from the Daniudi Gas Field, Ordos Basin were collected for central and terminal carbon isotope measurements in propane. Similar δ13C values of central carbon of propane in natural gas from the Ordovician and Carboniferous-Permian reservoirs could be indicative of the same source strata. While 13C-enrichment in the terminal C-atom of propane in natural gas from the Carboniferous-Permian reservoirs probably indicates that natural gas accumulated in the Carboniferous-Permian reservoir maybe have experienced a higher thermal maturation compared to that from the Ordovician reservoirs. The results suggest that the PSIA in propane can be a potentially powerful tool to probe the mechanisms on natural gas generation.
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Key words:
- stable isotope /
- position-specific carbon isotope /
- propane /
- natural gas /
- Ordos Basin
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图 6 鄂尔多斯盆地大牛地气田奥陶系马五段与石炭—二叠系储集层天然气成因判识图[39]
Figure 6. Genetic identification of natural gas in 5th member of Ordovician Majiagou Formation and Carboniferous-Permian reservoirs, Daniudi Gas Field, Ordos Basin
表 1 天然气样品基础数据
Table 1. Basic data of natural gas samples
样品 层位 天然气组分含量/% 碳同位素δ13CVPDB/‰ H2 N2 CO2 CH4 C2H6 C3H8 iC4H10 nC4H10 iC5H12 nC5H12 C1 C2 C3 G 12.89 2.82 0.84 73.64 4.03 2.35 0.58 1.77 0.36 0.71 -44.3 -40.5 -34.3 DPF-305 O1m5 0.13 0.01 4.48 92.78 2.15 0.37 0.08 -37.5 -27.4 -27.5 D12-8 P1s1- P1x1 0.33 0.14 2.18 87.81 6.72 1.92 0.30 0.45 0.15 -37.2 -25.6 -25.5 表 2 标准天然气样G中丙烷裂解分馏因子及位碳同位素组成
Table 2. Enrichment factors and absolute δ13C values of position-specific carbons of propane pyrolysis in standard natural gas G
‰ 裂解温度/℃ ε1 ε2 ε3 δ13Ca δ13Cb 计算值δ13C丙烷 实测值δ13C丙烷 偏差 740 -5.3 -0.1 -6.7 -36.5 -30.1 -34.4 -34.3 0.1 760 -5.7 0.3 -4.1 -37.5 -28.2 -34.4 -34.3 0.1 780 -5.9 0.2 -5.9 -36.9 -29.6 -34.4 -34.3 0.1 800 -6.3 0.9 -4.2 -37.7 -28.1 -34.3 -34.3 0.2 820 -6.9 1.4 -4.6 -37.1 -29.3 -34.5 -34.3 0.2 840 -6.1 2.8 -4.3 -37.0 -29.6 -34.5 -34.3 0.2 860 -4.2 5.7 -4.0 -36.6 -30.5 -34.5 -34.3 0.2 880 -2.8 7.5 -4.1 -36.3 -31.0 -34.6 -34.3 0.3 900 -1.2 9.3 -4.6 -37.1 -29.8 -34.7 -34.3 0.4 注:ε1、ε2、ε3分别为丙烷瞬时裂解的3个主要反应的分馏因子(见图 4);δ13Ca为丙烷端位碳同位素值;δ13Cb为丙烷中间位碳同位素值。 表 3 鄂尔多斯盆地大牛地气田天然气样品丙烷位碳同位素组成
Table 3. Absolute δ13C values of position-specific carbons of propane in Daniudi Gas Field, Ordos Basin
‰ 样品号 层位 δ13Ca δ13Cb δ13Ca-δ13Cb 计算值δ13C丙烷 实测值δ13C丙烷 DPF-305 O1m5 -27.1 -28.9 1.8 -27.7 -27.5 D12-8 P1s1- P1x1 -23.4 -29.6 6.2 -25.4 -25.5 -
[1] GALIMOV E M, IVLEV A A, KUZNETSOVA N G. Carbon isotope composition of gaseous hydrocarbons in petroleum and the problem of their origin[J]. Geochem Int, 1970, 7: 594-603. [2] STAHL W, CAREY B D. Source-rock identification by isotope analyses of natural gases from fields in the Val Verde and Delaware basins, West Texas[J]. Chemical Geology, 1975, 16(4): 257-267. doi: 10.1016/0009-2541(75)90065-0 [3] SCHOELL M. The hydrogen and carbon isotopic composition of methane from natural gases of various origins[J]. Geochimica et Cosmochimica Acta, 1980, 44(5): 649-661. doi: 10.1016/0016-7037(80)90155-6 [4] 戴金星, 戚厚发, 宋岩. 鉴别煤成气和油型气若干指标的初步探讨[J]. 石油学报, 1985, 6(2): 31-38. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB198502007.htmDAI Jinxing, QI Houfa, SONG Yan. On the indicators for identi-fying gas from oil and gas from coal measure[J]. Acta Petrolei Sinica, 1985, 6(2): 31-38. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB198502007.htm [5] CHUNG H M, GORMLY J R, SQUIRES R M. Origin of gaseous hydrocarbons in subsurface environments: theoretical considerations of carbon isotope distribution[J]. chemical Geology, 1988, 71(1/3): 97-104. [6] WHITICAR M J. Correlation of natural gases with their sources[M]//MAGOON L B, DOW W G. AAPG memoir 60, the petroleum system-from source to trap. Tulsa: American Association of Petroleum Geologists, 1994: 261-283. [7] 宋岩, 徐永昌. 天然气成因类型及其鉴别[J]. 石油勘探与开发, 2005, 32(4): 24-29. doi: 10.3321/j.issn:1000-0747.2005.04.004SONG Yan, XU Yongchang. Origin and identification of natural gases[J]. Petroleum Exploration and Development, 2005, 32(4): 24-29. doi: 10.3321/j.issn:1000-0747.2005.04.004 [8] LIU Changjie, MCGOVERN G P, LIU Peng, et al. Position-specific carbon and hydrogen isotopic compositions of propane from natural gases with quantitative NMR[J]. Chemical Geology, 2018, 491: 14-26. doi: 10.1016/j.chemgeo.2018.05.011 [9] LI Xiaoqiang, MCGOVERN G P, HORITA J. Kinetics of propane cracking and position-specific isotope fractionation: insights into the origins of natural gases[J]. Organic Geochemistry, 2021, 155: 104234. doi: 10.1016/j.orggeochem.2021.104234 [10] GAO Li, HE Panqing, JIN Yanqi, et al. Determination of position-specific carbon isotope ratios in propane from hydrocarbon gas mixtures[J]. Chemical Geology, 2016, 435: 1-9. doi: 10.1016/j.chemgeo.2016.04.019 [11] GILBERT A, LOLLAR B S, MUSAT F, et al. Intramolecular isotopic evidence for bacterial oxidation of propane in subsurface natural gas reservoirs[J]. Proceedings of the National Academy of Sciences of the United States of America, 2019, 116(14): 6653-6658. doi: 10.1073/pnas.1817784116 [12] PETERSON B K, FORMOLO M J, LAWSON M. Molecular and detailed isotopic structures of petroleum: kinetic Monte Carlo analysis of alkane cracking[J]. Geochimica et Cosmochimica Acta, 2018, 243: 169-185. doi: 10.1016/j.gca.2018.09.012 [13] LIU Changjie, LIU Peng, MCGOVERN G P, et al. Molecular and intramolecular isotope geochemistry of natural gases from the Woodford shale, Arkoma Basin, Oklahoma[J]. Geochimica et Cosmochimica Acta, 2019, 255: 188-204. doi: 10.1016/j.gca.2019.04.020 [14] ZHAO Heng, LIU Changjie, LARSON T E, et al. Bulk and position-specific isotope geochemistry of natural gases from the Late Cretaceous Eagle Ford shale, south Texas[J]. Marine and Petroleum Geology, 2020, 122: 104659. doi: 10.1016/j.marpetgeo.2020.104659 [15] ABELSON P H, HOERING T C. Carbon isotope fractionation in formation of amino acids by photosynthetic organisms[J]. Proceedings of the National Academy of Sciences of the United States of America, 1961, 47(5): 623-632. doi: 10.1073/pnas.47.5.623 [16] CORSO T N, BRENNA J T. High-precision position-specific isotope analysis[J]. Proceedings of the National Academy of Sciences of the United States of America, 1997, 94(4): 1049-1053. doi: 10.1073/pnas.94.4.1049 [17] GILBERT A, HATTORI R, SILVESTRE V, et al. Comparison of IRMS and NMR spectrometry for the determination of intramolecular 13C isotope composition: application to ethanol[J]. Talanta, 2012, 99: 1035-1039. doi: 10.1016/j.talanta.2012.05.023 [18] GILBERT A, YAMADA K, YOSHIDA N. Exploration of intramolecular 13C isotope distribution in long chain n-alkanes (C11-C31) using isotopic 13C NMR[J]. Organic Geochemistry, 2013, 62: 56-61. doi: 10.1016/j.orggeochem.2013.07.004 [19] ROSSMANN A, BUTZENLECHNER M, SCHMIDT H L. Evidence for a nonstatistical carbon isotope distribution in natural glucose[J]. Plant Physiology, 1991, 96: 609-614. doi: 10.1104/pp.96.2.609 [20] HUANG D S, WU S H, WANG Y S, et al. Determination of the carbon kinetic isotope effects on propane hydroxylation mediated by the methane monooxygenases from Methylococcus capsulatus (Bath) by using stable carbon isotopic analysis[J]. ChemBioChem, 2002, 3(8): 760-765. doi: 10.1002/1439-7633(20020802)3:8<760::AID-CBIC760>3.0.CO;2-K [21] CORSO T N, LEWIS B A, BRENNA J T. Reduction of fatty acid methyl esters to fatty alcohols to improve volatility for isotopic analysis without extraneous carbon[J]. Analytical Chemistry, 1998, 70(18): 3752-3756. doi: 10.1021/ac9802527 [22] HATTORI R, YAMADA K, KIKUCHI M, et al. Intramolecular carbon isotope distribution of acetic acid in vinegar[J]. Journal of Agricultural and Food Chemistry, 2011, 59(17): 9049-9053. doi: 10.1021/jf200227e [23] GILBERT A, YAMADA K, YOSHIDA N. Accurate method for the determination of intramolecular 13C isotope composition of ethanol from aqueous solutions[J]. Analytical Chemistry, 2013, 85: 6566-6570. doi: 10.1021/ac401021p [24] GILBERT A, YAMADA K, SUDA K, et al. Measurement of position-specific 13C isotopic composition of propane at the nanomole level[J]. Geochimica et Cosmochimica Acta, 2016, 177: 205-216. doi: 10.1016/j.gca.2016.01.017 [25] LI Yun, ZHANG Lin, XIONG Yongqiang, et al. Determination of position-specific carbon isotope ratios of propane from natural gas[J]. Organic Geochemistry, 2018, 119: 11-21. doi: 10.1016/j.orggeochem.2018.02.007 [26] PIASECKI A, SESSIONS A L, LAWSON M, et al. Analysis of the site-specific carbon isotope composition of propane by gas source isotope ratio mass spectrometer[J]. Geochimica et Cosmochimica Acta, 2016, 188: 58-72. doi: 10.1016/j.gca.2016.04.048 [27] PIASECKI A, SESSIONS A, PETERSON B, et al. Prediction of equilibrium distributions of isotopologues for methane, ethane and propane using density functional theory[J]. Geochimica et Cosmochimica Acta, 2016, 190: 1-12. doi: 10.1016/j.gca.2016.06.003 [28] PIASECKI A, SESSIONS A, LAWSON M, et al. Position-specific 13C distributions within propane from experiments and natural gas samples[J]. Geochimica et Cosmochimica Acta, 2018, 220: 110-124. doi: 10.1016/j.gca.2017.09.042 [29] LIU Quanyou, JIN Zhijun, MENG Qingqiang, et al. Genetic types of natural gas and filling patterns in Daniudi gas field, Ordos Basin, China[J]. Journal of Asian Earth Sciences, 2015, 107: 1-11. doi: 10.1016/j.jseaes.2015.04.001 [30] WU Xiaoqi, LIU Quanyou, ZHU Jianhui, et al. Geochemical characteristics of tight gas and gas-source correlation in the Daniudi gas field, the Ordos Basin, China[J]. Marine and Petroleum Geology, 2017, 79: 412-425. doi: 10.1016/j.marpetgeo.2016.10.022 [31] 孙晓, 王杰, 陶成, 等. 鄂尔多斯盆地大牛地下古生界天然气地球化学特征及其来源综合判识[J]. 石油实验地质, 2021, 43(2): 307-314. doi: 10.11781/sysydz202102307SUN Xiao, WANG Jie, TAO Cheng, et al. Evaluation of geochemical characteristics and source of natural gas in Lower Paleozoic, Daniudi area, Ordos Basin[J]. Petroleum Geology & Experiment, 2021, 43(2): 307-314. doi: 10.11781/sysydz202102307 [32] WU Xiaoqi, ZHU Jianhui, NI Chunhua, et al. Genetic types and sources of Lower Paleozoic natural gas in the Daniudi gas field, Ordos Basin, China[J]. Energy Exploration & Exploitation, 2017, 35(2): 218-236. [33] 戴金星, 邹才能, 陶士振, 等. 中国大气田形成条件和主控因素[J]. 天然气地球科学, 2007, 18(4): 473-484. doi: 10.3969/j.issn.1672-1926.2007.04.001DAI Jinxing, ZOU Caineng, TAO Shizhen, et al. Formation conditions and main controlling factors of large gas fields in China[J]. Natural Gas Geoscience, 2007, 18(4): 473-484. doi: 10.3969/j.issn.1672-1926.2007.04.001 [34] 杨华, 刘新社. 鄂尔多斯盆地古生界煤成气勘探进展[J]. 石油勘探与开发, 2014, 41(2): 129-137. https://www.cnki.com.cn/Article/CJFDTOTAL-SKYK201402002.htmYANG Hua, LIU Xinshe. Progress of Paleozoic coal-derived gas exploration in Ordos Basin, West China[J]. Petroleum Exploration and Development, 2014, 41(2): 129-137. https://www.cnki.com.cn/Article/CJFDTOTAL-SKYK201402002.htm [35] 杨智, 何生, 邹才能, 等. 鄂尔多斯盆地北部大牛地气田成岩成藏耦合关系[J]. 石油学报, 2010, 31(3): 373-378. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB201003004.htmYANG Zhi, HE Sheng, ZOU Caineng, et al. Coupling relationship between reservoir diagenesis and natural gas accumulation of Daniudi Gas Field in North Ordos Basin[J]. Acta Petrolei Sinica, 2010, 31(3): 373-378. https://www.cnki.com.cn/Article/CJFDTOTAL-SYXB201003004.htm [36] 黄第藩, 熊传武, 杨俊杰, 等. 鄂尔多斯盆地中部气田气源判识和天然气成因类型[J]. 天然气工业, 1996, 16(6): 1-5. https://www.cnki.com.cn/Article/CJFDTOTAL-TRQG606.000.htmHUANG Difan, XIONG Chuanwu, YANG Junjie, et al. Gas source discrimination and natural gas genetic types of Central Gas Field in E'Erduosi Basin[J]. Natural Gas Industry, 1996, 16(6): 1-5. https://www.cnki.com.cn/Article/CJFDTOTAL-TRQG606.000.htm [37] 李贤庆, 胡国艺, 李剑, 等. 鄂尔多斯盆地中部气田天然气混源的地球化学标志与评价[J]. 地球化学, 2003, 32(3): 282-290. https://www.cnki.com.cn/Article/CJFDTOTAL-DQHX200303009.htmLI Xianqing, HU Guoyi, LI Jian, et al. Geochemical indexes and evaluation of mixed origin natural gases from Central Gas Field in the Ordos Basin[J]. Geochimica, 2003, 32(3): 282-290. https://www.cnki.com.cn/Article/CJFDTOTAL-DQHX200303009.htm [38] DAI Jinxing, LI Jian, LUO Xia, et al. Stable carbon isotope compositions and source rock geochemistry of the giant gas accumulations in the Ordos Basin, China[J]. Organic Geochemistry, 2005, 36(12): 1617-1635. [39] TISSOT B P, WELTE D H. Petroleum formation and occurrence[M]. Berlin: Springer-Verlag, 1984.