富油煤是一种在我国西北部地区广泛分布的煤基油气资源，其中煤焦油资源的开发利用有助于改善能源供给格局从而保障国家能源安全。然而，富油煤在不同区域、层位存在显著的非均匀分布特点。在宏观上，富油煤焦油产率的成煤环境约束有待深化；在微观上，影响焦油产率的关键分子结构类型有待明晰，宏微观内在联系有待阐释。鄂尔多斯盆地和三塘湖盆地富油煤品质优异，因此，本研究以鄂尔多斯盆地延安组煤和三塘湖盆地八道湾组富油煤为对象，通过元素地球化学、亚显微组分分析等手段对富油煤成煤沼泽的水介质条件和煤相特点进行深入研究，结合红外光谱、¹³C核磁共振和索式抽提+GC-MS等方法系统研究富油煤原煤及镜质组关键大分子结构与小分子化合物组成，最终揭示关键分子结构的成煤环境约束效应。

研究表明：（1）物质组成上，富油煤具备高挥发分、高镜质组、高H/C原子比的特点；沉积环境上，富油煤形成于陆源碎屑供给少，温暖潮湿的强还原环境中，低位泥炭沼泽和潮湿森林沼泽中，木本组织少、覆水较深条件更有助于形成高焦油产率煤。水介质的古盐度对焦油产率控制性较弱，还原性条件对其控制较强。（2）富油煤大分子骨架结构与抽提小分子化合物都对焦油产率有所贡献，且大分子影响更强。其中脂肪官能团具有积极影响，并主要体现在亚甲基结构上，而表征缩合程度和含氧结构的参数对焦油产率有所抑制，小分子化合物中的低碳数正构烷烃和低环数芳香烃等富氢结构均对焦油产率有积极影响。此类影响富油煤的关键分子结构也受控于成煤环境，凝胶化程度越高、植物保存指数越低、植被指数低，煤中富氢结构越丰富。（3）单纯镜质组的焦油产率在不同盆地间、同盆地不同煤层、同煤层不同部位也存在差异，且差异逐级变小，既成煤环境越接近，镜质组焦油产率也越接近。镜质组富氢结构参数对焦油产率的影响机制与原煤近乎一致，同样受控于脂肪族官能团、脂肪族碳以及轻质小分子化合物。同样，低木本、深覆水、高分解程度的成煤环境中镜质组关键分子结构也更高。

Tar-rich coal is a prevalent resource in the northwest China, possessing a unique combination of coal, oil, and gas. The utilization of it can effectively alleviate the challenge of fossil energy. However, tar-rich coal exhibits significant heterogeneity in different regions and coal seams. Macroscopically, the correlation between tar yield and coal-forming environment needs to be further deepened; Microscopically, the key molecular structure affecting tar yield need to be clarified, and the connection between macro and micro is important. In this regard, the study focus on tar-rich coal from the Yan'an Formation in the Ordos Basin and the Badaowan Formation in the Santanghu Basin. Combining elemental geochemistry and maceral to study the coal-forming environment. Above this, using FT-IR, ¹³C-NMR, and Soxhlet extraction+GC-MS to study the key macromolecular structures and small molecule compound of the coal and vitrinite. Ultimately, reveal the influence of coal-forming environment on key molecular structures.

The result shows: (1) Tar-rich coal was characterized by high volatile content, high vitrinite content, and a high H/C ratio. It was usually formed in limnic and wet forest swamps with strong reducing conditions, limited land debris, and a warm and humid climate. Among them, low woody tissues and deep overlying water were favorable for the formation of tar-rich coal. (2) Both the macromolecular skeleton and small molecule compounds contributed to the tar yield. Besides, aliphatic functional groups, particularly methylene, played a positive role in tar yield. The degree of condensation and the presence of oxygen-containing structures can inhibit tar yield. Small molecule compounds such as low-carbon n-alkanes and low-ring aromatic hydrocarbons had a positive effect on tar yield. The structures were also affected by the coal-forming environment; low GI, high TPI, and VI contributed to this type of structure. (3) The tar yield of the vitrinite also varies between basins, the coal seams in the same basin, and the different parts of the same coal seam, although these differences tend to decrease gradually. The effect of the hydrogen-rich structure on tar yield was also controlled by the aliphatic functional groups and lightweight small molecule compounds. Additionally, the key molecular structure of vitrinite was also formed in the coal-forming environment with low woody, deep overlying water and low tissue preservation.

[1] 王双明, 申艳军, 宋世杰等. “双碳”目标下煤炭能源地位变化与绿色低碳开发[J]. 煤炭报, 2023, 48 (07): 2599-2612.

[2] 樊大磊, 王宗礼, 李剑等. 2023年国内外油气资源形势分析及展望. [J]. 中国矿业, 2024, 33(01): 30-37.

[3] 段中会, 马丽, 傅德亮等. 大保当井田富油煤地下原位热解开发前景展望[J]. 中国煤炭地质, 2023 , 35(08): 1-6.

[4] 王双明, 师庆民, 王生全等. 富油煤的油气资源属性与绿色低碳开发[J]. 煤炭学报, 2021, 46(05): 1365-1377.

[5] 王双明, 王虹, 任世华等. 西部地区富油煤开发利用潜力分析和技术体系构想[J].中国工程科学, 2022, 24(03): 49-57.

[6] 惠一凡, 赵习民, 冯烁等. 新疆三塘湖盆地富油煤赋存特征及主控因素[J]. 煤炭技术, 2023, 42(08): 117-123.

[7] 张天印, 冯烁, 李鑫等. 富油煤分子结构对生烃潜力影响研究[J]. 新疆地质, 2023, 41(S1): 61.

[8] 鲍园, 李争岩, 安超等. 多手段表征富油煤微生物厌氧发酵孔隙结构变化特征及机制[J]. 煤炭学报, 2023, 48(02): 891-899.

[9] Stanton R W, Warwick P D, Swanson S M. Tar yields from low-temperature carbonization of coal facies from the Powder River Basin, Wyoming, USA[J]. International journal of coal geology, 2005, 63(1-2): 13-26.

[10] Petersen H I, Nytoft H P. Oil generation capacity of coals as a function of coal age and aliphatic structure[J]. Organic Geochemistry, 2006, 37(5): 558-583.

[11] Marshall C, Large D J, Meredith W, et al. Geochemistry and petrology of Palaeocene coals from Spitsbergen—Part 1: Oil potential and depositional environment[J]. International Journal of Coal Geology, 2015, 143: 22-33.

[12] Lin Y, Wang S, Yang Z, et al. Characteristics of Hydrogen-rich Coals in Southern China: Implications from Organic Geochemistry and Carbon Isotopic Compositions[J]. Acta Geologica Sinica‐English Edition, 2022, 96(1): 309-320.

[13] 许婷, 李宁, 姚征. 榆横矿区3~#煤层富油煤的煤岩煤质及成煤环境[J]. 煤炭技术, 2022, 41(07): 82-85.

[14] 马丽, 王双明, 段中会等. 陕西省富油煤资源潜力及开发建议[J]. 煤田地质与勘探, 2022, 50(02): 1-8.

[15] 姚征, 罗乾周, 李宁等. 陕北石炭-二叠纪富油煤赋存特征及影响因素 [J]. 煤田地质与勘探, 2021, 49(03): 50-61+68.

[16] 王锐, 夏玉成, 马丽. 榆神矿区富油煤赋存特征及其沉积环境研究[J]. 煤炭科学技术, 2020, 48(12):192-197.

[17] 谢青, 李宁, 姚征等. 黄陵矿区富油煤焦油产率特征及主控地质因素分析[J]. 中国煤炭, 2020, 46(11): 83-90.

[18] 杨甫, 段中会, 马丽等. 陕西省富油煤分布及受控地质因素[J]. 煤炭科学技术, 2023, 51(03): 171-181.

[19] 李焕同, 朱志蓉, 张战波等. 柠条塔煤矿富油煤赋存特征及其成煤环境控制[J]. 煤炭技术, 2022, 41(04): 63-66.

[20] 石磊. 煤共价键结构在热解过程中的阶段解离研究[D]. 北京： 北京化工大学, 2014.

[21] Liu P, Zhang D, Wang L, et al. The structure and pyrolysis product distribution of lignite from different sedimentary environment[J]. Applied Energy, 2016, 163: 254-262.

[22] Li X, Xue Y, Feng J, et al. Co-pyrolysis of lignite and Shendong coal direct liquefaction residue. Fuel 2015;144:342–8.

[23] Hayashi J, Kawakami T, Kusakabe K, et al. Physical and chemical modification of low-rank coals with alkyl chains and the roles of incorporated groups in pyrolysis. Energy Fuels 1993;7:1118–22.

[25]Zhang D, Liu P, Lu X, et al. Upgrading of low rank coal by hydrothermal treatment: Coal tar yield during pyrolysis[J]. Fuel Processing Technology, 2016, 141: 117-122.

[26] 刘池洋, 赵红格, 桂小军等. 鄂尔多斯盆地演化-改造的时空坐标及其成藏(矿)响应[J]. 地质学报, 2006, (05): 617-638.

[27] Jin R, Yu R, Yang J, et al. Paleo-environmental constraints on uranium mineralization in the Ordos Basin: Evidence from the color zoning of U-bearing rock series[J]. Ore Geology Reviews, 2019, 104: 175-189.

[28] 王东东. 鄂尔多斯盆地中侏罗世延安组层序—古地理与聚煤规律[D]. 北京: 中国矿业大学(北京), 2012.

[29] Ma J, Huang Z, Liang S, et al. Geochemical and tight reservoir characteristics of sedimentary organic-matter-bearing tuff from the Permian Tiaohu Formation in the Santanghu Basin, Northwest China. Marine and Petroleum Geology, 2016, 73, 405-418.

[30] Liu X, Liu C. Tectonic evolution and prototype basins of Santanghu basin. Journal of Southwest Petroleum University (Science & Technology Edition), 2002 24, 13.

[31] 张雨瑶. 新疆三塘湖煤田汉水泉矿区高砷煤中砷的赋存状态及地质成因研究[D]. 乌鲁木齐: 新疆大学, 2018.

[32] Pickel W, Kus J, Flores D, et al. Classification of liptinite–ICCP System 1994[J]. International Journal of Coal Geology, 2017, 169: 40-61.

[33] 王美君, 杨会民, 何秀风等. 铁基矿物质对西部煤热解特性的影响[J]. 中国矿业大学学报, 2010, 39(03): 426-430.

[34] 马家亮, 高政, 张佳为等. 阴山矿区南阳坡6~#煤的煤岩特征及古环境研究[J]. 煤炭技术, 2017, 36(12): 93-95.

[35] 陈云云. 山西平朔矿区4号煤地球化学特征及古环境意义[D]. 北京: 中国地质大学(北京), 2017.

[36] Shi Q, Mi Y, Wang S, et al. Pyrolysis behavior of tar-rich coal with various coal-forming environments: A TGA and in-situ transmission FTIR study[J]. Fuel, 2024, 358: 130250.

[37] Gmur D, Kwiecińska B K. Facies analysis of coal seams from the Cracow sandstone series of the upper Silesia Coal Basin, Poland[J]. International Journal of Coal Geology, 2002, 52(1-4): 29-44.

[38] Singh V P, Singh B D, Mathews R P, et al. Investigation on the lignite deposits of Surkha mine (Saurashtra Basin, Gujarat), western India: Their depositional history and hydrocarbon generation potential[J]. International Journal of Coal Geology, 2017, 183: 78-99.

[39] Jiu B, Huang W, Hao R, 2021. A method for judging depositional environment of coal reservoir based on coal facies parameters and rare earth element parameters. J. Petrol. Sci. Eng. 207, 109128.

[40] 李贤庆, 赵师庆, 曾凡刚. 腐殖煤的显微组分与生烃研究──以南华北太原组、山西组煤为例[J]. 中国煤田地质, 1995, (04): 46-51.

[41] 陈建平, 赵长毅, 何忠华. 煤系有机质生烃潜力评价标准探讨[J]. 石油勘探与开发, 1997, 24(1): 1-5

[42] 赵伟, 张晓欠, 周安宁等. 神府煤煤岩显微组分的浮选分离及富集物的低温热解产物特性研究[J]. 燃料化学学报, 2014, 42(5): 527-533

[43] Liu B, Spiekermann R, Zhao C, et al. Evidence for the repeated occurrence of wildfires in an upper Pliocene lignite deposit from Yunnan, SW China[J]. International Journal of Coal Geology, 2022, 250: 103924.

[44] Panda M, Equeenuddin S M, Mohanty D. Organic petrography and stable isotopic characteristics of Permian Talcher coal, India: Implications on depositional environment[J]. International Journal of Coal Geology, 2022, 264: 104130.

[45] Diessel, C.F.K., 1992. Coal-bearing Depositional Systems. Springer-Verlag, Berlin.

[46] Calder J H, Gibling M R, Mukhopadhyay P K. Peat formation in a westphalian B piedmont setting, cumberland basin, Nova Scotia: Implications for the maceral-based interpretation of rheotrophic and raised paleomires. Contribution series No. 91-002[J]. 1991.

[47] Diessel C F K. An appraisal of coal facies based on maceral characteristics[J]. Australian Coal Geology, 1982, 4(2): 474-484.

[48] 代世峰, 任德贻, 李生盛等. 内蒙古准格尔黑岱沟主采煤层的煤相演替特征[J]. 中国科学(D辑), 2007, 37(A01): 119-126

[49] Kimura T. Relationships between inorganic elements and minerals in coals from the Ashibetsu district, Ishikari coal field, Japan[J]. Fuel processing technology, 1998, 56(1-2): 1-19.

[50] Dai S, Chou C L. Occurrence and origin of minerals in a chamosite-bearing coal of Late Permian age, Zhaotong, Yunnan, China[J]. American Mineralogist, 2007, 92(8-9): 1253-1261.

[51] Huang H, Du Y, Huang Z, et al. Depositional chemistry of chert during late Paleozoic from western Guangxi and its implication for the tectonic evolution of the Youjiang Basin. Sci. China Earth Sci, 2013, 56 (3), 479–493.

[52] 代世峰, 任德贻, 唐跃刚. 煤中常量元素的赋存特征与研究意义[J]. 煤田地质与勘探, 2005, 33(2): 1-5

[53] 黄文辉, 杨起, 汤达祯等. 华北晚古生代煤的稀土元素地球化学特征[J]. 地质学报, 1999, 73(4): 360-369

[54] Gao J, Zhang Y, Meng D, et al., 2019. Effect of ash and dolomite on the migration of sulfur from coal pyrolysis volatiles. J. Anal. Appl. Pyrol. 140, 349–354.

[55] Kolditz K, Dellwig O, Barkowski J, et al. Geochemistry of Holocene salt marsh and tidal flat sediments on a barrier island in the southern North Sea (Langeoog, North‐west Germany)[J]. Sedimentology, 2012, 59(2): 337-355.

[56] Fu J, Li S, Xu L, et al. Paleo-sedimentary environmental restoration and its significance of Chang 7 Member of Triassic Yanchang Formation in Ordos Basin, NW China[J]. Petroleum Exploration and Development, 2018, 45(6): 998-1008.

[57] Jiang Q, Ma Y, Shen Y, et al. High-frequency redox variations of the Eocene cyclic lacustrine sediments in the Yingxi area, western Qaidam Basin, China[J]. Journal of Asian Earth Sciences, 2019, 174: 135-151.

[58] Paytan A, Averyt K, Faul K, et al. Barite accumulation, ocean productivity, and Sr/Ba in barite across the Paleocene–Eocene Thermal Maximum[J]. Geology, 2007, 35(12): 1139-1142.

[59] Mejjad N, Laissaoui A, El-Hammoumi O, et al. Sediment geochronology and geochemical behavior of major and rare earth elements in the Oualidia Lagoon in the western Morocco[J]. Journal of Radioanalytical and Nuclear Chemistry, 2016, 309(3): 1133-1143.

[60] Ketris M P, Yudovich Y E. Estimations of Clarkes for Carbonaceous biolithes: World averages for trace element contents in black shales and coals[J]. International journal of coal geology, 2009, 78(2): 135-148.

[61] 田洋, 赵小明, 牛志军等. 鄂西南利川二叠纪吴家坪组硅质岩成因及沉积环境[J]. 沉积学报, 2013, 31(4): 590-599.

[62] 孙立新, 张云, 张天福等. 鄂尔多斯北部侏罗纪延安组、直罗组孢粉化石及其古气候意义[J]. 地学前缘, 2017, 24(1): 32-51

[63] 李得路. 鄂尔多斯盆地南部三叠系延长组长7油页岩地球化学特征及古沉积环境分析[D]. 西安: 长安大学, 2018.

[64] Huang X, Qian Z, Lu D, et al. Element geochemistry and depositional setting of Ordovician Miboshan Formation in central-southern Helan Mountain[J]. Acta Geoscientica Sinica, 2009, 30: 65-71.

[65] Kortenski J. Carbonate minerals in Bulgarian coals with different degrees of coalification[J]. International journal of coal geology, 1992, 20(3-4): 225-242.

[66] 张双全, 煤化学[M] 徐州: 中国矿业大学出版社, 2019.

[67] Zhang J, Wei C, Zhao C, et al. Effects of nano-pore and macromolecule structure of coal samples on energy parameters variation during methane adsorption under different temperature and pressure[J]. Fuel, 2021, 289: 119804.

[68] Liu J, Jiang Y, Yao W, et al. Molecular characterization of Henan anthracite coal[J]. Energy & Fuels, 2019, 33(7): 6215-6225.

[69] 王华, 杜美利, 张国涛. 石马洼煤显微组分结构特征的红外光谱分析[J]. 煤炭转化, 2015, 38(03): 5-11.

[70] He X, Liu X, Nie B, et al. FTIR and Raman spectroscopy characterization of functional groups in various rank coals[J]. Fuel, 2017, 206: 555-563

[71] 李焕同, 朱志蓉, 乔军伟等. 陕北侏罗纪富镜煤和富惰煤分子结构的FTIR, XPS和13C NMR表征[J]. 光谱学与光谱分析, 2022, 42(8): 2624-2630.

[72] Liu Shengyu. The fate of organic oxygen during coal pyrolysis[J]. Energy sources, 2003, 25(5): 479-488.

[73] Chen J, Jia W, Yu C, et al. Bound hydrocarbons and structure of pyrobitumen rapidly formed by asphaltene cracking: Implications for oil–source correlation[J]. Organic Geochemistry, 2020, 146: 104053.

[74] Hou L, Ma W, Luo X, et al. Chemical structure changes of lacustrine Type-II kerogen under semi-open pyrolysis as investigated by solid-state 13C NMR and FT-IR spectroscopy[J]. Marine and Petroleum Geology, 2020, 116: 104348.

[75] Chen J, Jia W, Yu C, et al. Bound hydrocarbons and structure of pyrobitumen rapidly formed by asphaltene cracking: Implications for oil–source correlation[J]. Organic Geochemistry, 2020, 146: 104053.

[76]You Y, Han X, Liu J, et al. Structural characteristics and pyrolysis behaviors of huadian oil shale kerogens using solid-state 13C NMR, Py-GCMS and TG[J]. J Therm Anal Calorim 2018;131(2):1845–55

[77] Yan J, Lei Z, Li Z, et al. Molecular structure characterization of low-medium rank coals via XRD, solid state 13C NMR and FTIR spectroscopy[J]. Fuel, 2020, 268: 117038

[78] Yoshida T, Tokuhashi K, Maekawa Y. Liquefaction reaction of coal: 1. Depolymerization of coal by cleavages of ether and methylene bridges[J]. Fuel, 1985, 64(7): 890-896.

[79] Solomon P R, King H H. Tar evolution from coal and model polymers: Theory and experiments[J]. Fuel, 1984, 63(9): 1302-1311.

[80] Bai H, Mao N, Wang R, et al. Kinetic characteristics and reactive behaviors of HSW vitrinite coal pyrolysis: A comprehensive analysis based on TG-MS experiments, kinetics models and ReaxFF MD simulations[J]. Energy Reports, 2021, 7: 1416-1435

[81] Miura K. Mild conversion of coal for producing valuable chemicals[J]. Fuel processing technology, 2000, 62(2-3): 119-135.

[82] Zhou S, Liu D, Cai Y, et al. Gas sorption and flow capabilities of lignite, subbituminous and high-volatile bituminous coals in the Southern Junggar Basin, NW China[J]. Journal of Natural Gas Science and Engineering, 2016, 34: 6-21.

[83] 谢克昌. 煤的结构与反应性[M]. 北京: 科学出版社, 2002.

[84] Li Y, Huang S, Wu Y, et al. The roles of the low molecular weight compounds in the low-temperature pyrolysis of low-rank coal [J]. Journal of the Energy Institute, 2019, 92(2): 203-209

[85] Zhu P, Luo A Q, Zhang F, et al. Effects of extractable compounds on the structure and pyrolysis behaviours of two Xinjiang coal [J]. Journal of Analytical & Applied Pyrolysis, 2018, 133: 128-135

[86] Tian B, Qiao Y, Bai L, et al. Pyrolysis behavior and kinetics of the trapped small molecular phase in a lignite[J]. Energy Conversion and Management, 2017, 140: 109-120.

[87] 李新. 高变质程度高硫煤的有机地球化学特征[D]. 邯郸: 河北工程大学, 2022.

[88] Zhao Q, Qin S, Shen W, et al. Significant influence of different sulfur forms on Sulfur-containing polycyclic aromatic compound formation in high-sulfur coals[J]. Fuel, 2023, 332: 125999.

[89] 杨永华, 华晓梅, 陈素玲等. 芳香族化合物生物降解代谢及其分子遗传研究[J]. 环境科学进展, 1995, 3(6): 31-43

[90] 高康. 重庆中梁山和磨心坡晚二叠世煤的地球化学特征[D]. 邯郸: 河北工程大学, 2017.

[91] 师庆民, 王双明, 王生全等. 神府南部延安组富油煤多源判识规律[J]. 煤炭学报, 2022, 47(5): 2057-2066

[92] 师庆民, 米奕臣, 王双明等. 富油煤热解流体滞留特征及其机制[J]. 煤炭学报, 2022,47(3): 1329-1337

[93] 白翔, 邹达, 马凤云等. 低变质煤结构分析及其与热解焦油产率关联性研究[J]. 洁净煤技术, 2020, 26(4): 90-97

[94] 乐嘉炜. 煤中小分子化合物及催化剂对煤热解产物分布的影响[D]. 上海: 华东理工大学, 2017.

[95] 柳岩. 低分子化合物对煤热解/催化热解过程中轻质芳烃形成的影响[D]. 太原: 太原理工大学, 2020.

[96] Bausch M J, Guadalupe-Fasano C, Gostowski R. Estimates of solution-phase bond dissociation energies for carbon-sulfur and sulfur-sulfur bonds in radical anions derived from aromatic sulfides[J]. Energy & fuels, 1991, 5(3): 419-423.

[97] Davico G E, Bierbaum V M, DePuy C H, et al. The CH bond energy of benzene[J]. Journal of the American Chemical Society, 1995, 117(9): 2590-2599.

[98] Miura K, Mae K, Li W, et al. Estimation of hydrogen bond distribution in coal through the analysis of OH stretching bands in diffuse reflectance infrared spectrum measured by in-situ technique[J]. Energy & Fuels, 2001, 15(3): 599-610

[99] Arenillas A, Pevida C, Rubiera F, et al. Characterisation of model compounds and a synthetic coal by TG/MS/FTIR to represent the pyrolysis behaviour of coal[J]. Journal of Analytical and Applied Pyrolysis, 2004, 71(2): 747-763.

[100] Liu Q, Wang S, Zheng Y, et al. Mechanism study of wood lignin pyrolysis by using TG–FTIR analysis[J]. Journal of analytical and applied pyrolysis, 2008, 82(1): 170-177

[101] Pedley J B. Thermochemical data of organic compounds[M]. Springer Science & Business Media, 2012。

[102] Shi L, Liu Q, Guo X, et al. Pyrolysis behavior and bonding information of coal—A TGA study[J]. Fuel Processing Technology, 2013, 108: 125-132

[103] Given P H, Marzec A, Barton W A, et al. The concept of a mobile or molecular phase within the macromolecular network of coals: a debate[J]. Fuel, 1986, 65(2): 155-163.

[104] 相建华.不同煤级煤的结构特征及煤与CH4、CO2、H2O相互作用的分子模拟[D].太原: 太原理工大学, 2013.