Geochemical Characteristics and Organic Matter Enrichment Mechanism in Late Paleozoic Mudstone, Eastern Margin of Ordos Basin

YANG Jindong; YU Zhenfeng; GUO Xu; ZHAO Ruixi

doi:10.15898/j.ykcs.202306060075

2023 Vol. 42, No. 6

Article Contents

Article navigation > Rock and Mineral Analysis > 2023 > 42(6): 1104-1119

Next Article Previous Article

YANG Jindong, YU Zhenfeng, GUO Xu, ZHAO Ruixi. Geochemical Characteristics and Organic Matter Enrichment Mechanism in Late Paleozoic Mudstone, Eastern Margin of Ordos Basin[J]. Rock and Mineral Analysis, 2023, 42(6): 1104-1119. doi: 10.15898/j.ykcs.202306060075

Citation:

YANG Jindong, YU Zhenfeng, GUO Xu, ZHAO Ruixi. Geochemical Characteristics and Organic Matter Enrichment Mechanism in Late Paleozoic Mudstone, Eastern Margin of Ordos Basin[J]. Rock and Mineral Analysis, 2023, 42(6): 1104-1119. doi: 10.15898/j.ykcs.202306060075

Geochemical Characteristics and Organic Matter Enrichment Mechanism in Late Paleozoic Mudstone, Eastern Margin of Ordos Basin

Shanxi Lanyan Coalbed Methane Engineering Research Co., Ltd., Jincheng 048000, China

Received Date: 06 June 2023

Revised Date: 19 July 2023

Accepted Date: 21 August 2023

Publish Date: 31 December 2023

Abstract

Abstract

BACKGROUND
In the past two decades, with the development of CBM technology, the reduction of recoverable resources in shallow coalbed methane and the consumption of unconventional natural gas in China increasing year by year, the development of deep coalbed methane is imperative. The coalbed methane resources in China are about 30.05×10¹²m³, and the coalbed methane resource within the burial depth range from 1000m to 2000m is about 18.87×10¹²m³, accounting for 62.8% of the total resources, which reflects that deep coalbed methane is an important resource foundation for the large-scale development of China’s coalbed methane industry. As the second largest petroliferous basin in China, the Ordos basin has great potential for exploration of deep coalbed methane. In the Eastern Ordos Basin, the coalbed methane resource less than 1500m in depth is about 9×10¹²m³. Although the eastern edge of the Ordos Basin is rich in deep coalbed methane and tight sandstone gas, the enrichment characteristics and controlling factors of organic matter in coal-bearing strata are unclear, which is not conducive to the study on the storage law of resource, evaluation of development potential, and selection of favorable areas.
OBJECTIVES
To reveal the organic carbon content and its influencing factors of mudstones in the coal measure strata and guide the efficient development of coal-measure gas in the eastern margin of the Ordos Basin.
METHODS
(1) Analytical method: A total of 26 mudstone samples from the Shihezi, Shanxi and Taiyuan Formations were collected in the Shixi area. The content of major and trace elements, organic carbon content and clay mineral characteristics were tested by XRF, ICP-MS and SEM. Carbon isotope of Kerogen was determined by gas chromatography-isotope ratio mass spectrometry (GC-IRMS). The working standard of carbon isotope adopted the international standard PDB. (2) The mode of organic matter enrichment: Based on the experimental results, the Carboniferous—Permian sedimentary environment (including redox conditions, paleoclimate and terrigenous clastic characteristics) was studied with geochemical indicators, then correlation between sedimentary environment and organic matter content was further explored.
RESULTS
(1) Organic and elemental geochemical characteristics of muddy source rocks. Compared with the data of major elements in the upper crust of the North China Plate, the Carboniferous—Permian mudstone samples in the study area show significant enrichment of Al₂O₃ and TiO₂, and Al₂O₃/SiO₂ value ranges from 0.11 to 0.58 (mean value is 0.37), indicating that the sample has a high content of clay minerals. The trace elements are significant enrichment of Li and Cs, slight depletion of Sr, and significant depletion of Zn and Ba. Rare earth elements are highly enriched overall (mean value is 475.4μg/g), and higher than UCC (174.074μg/g) and PAAS (211.78μg/g). The organic carbon content of mudstone samples from the Shanxi and Taiyuan Formations in study area is relatively high (mean value is 2.87%), while the Shihezi Formation is relatively low (mean value is 0.72%).　　(2) Redox-sensitive elements, mainly including Mo, V, U, Ni, Ce and La, are important indicators for characterizing the oxidation environment of sedimentary water bodies. V/(V+Ni) values range from 0.61 to 0.89 (mean value is 0.75), and the differentiation of each layer is not obvious (mean value of Shihezi Formation is 0.79, Shanxi Formation is 0.74, Taiyuan Formation is 0.78), and Ce/La values range from 1.55-2.3 (mean value is 1.93). The above indicators exhibit the characteristics of a poor oxygen environment. The corrected CIA index ranges from 85 to 100, reflecting the strong weathering of parent rock in the source area under a hot-humid environment. Besides, the Sr/Cu and Mg/Ca values of the sample range from 3.16 to 24.89 (mean value is 7.43) and 0.34 to 7.98 (mean value is 2.91), respectively. Fe/Mn values range from 21.35455 to 545.72 (mean value is 202.25), indicating a warm and humid climate during the late Paleozoic. The clay mineral content in the terrestrial debris of the sample is relatively high, which consists mainly of kaolinite (mean value is 39.27%) and illite (mean value is 28.54%).　　 (3) The sedimentary period from the Taiyuan Formation to the Shihezi Formation belongs to a warm and humid climate as a whole, and the bottom of the sedimentary water body is in an anoxic environment. There was no significant correlation among climatic indices of Sr/Cu, Mg/Ca, Fe/Mn and TOC values, however, when the TOC value was more than 1, it was significantly positively correlated with Al and redox sensitive elements (RSEs).
CONCLUSIONS
The enrichment of organic matter in the argillaceous rock of the Taiyuan Formation and Shanxi Formation is controlled mainly by water redox conditions and terrigenous debris. The Shihezi Formation inherites the regressive trend of the eastern margin of the Ordos Basin in the late Paleozoic, and its sedimentary environment changes from shallow shelf to marine-continental transitional facies, causing a dynamic ambient and high energy circumstance, in which organic matter is not easily enriched and preserved.
- Ordos Basin /
- organic matter /
- enrichment mechanism /
- Shixi area /
- inductively coupled plasma-mass spectrometry /
- scanning electron microscope

FullText(HTML)

References

[1]	徐凤银, 侯伟, 熊先钺, 等. 中国煤层气产业现状与发展战略[J]. 石油勘探与开发, 2023, 50(4): 669−682. Google Scholar Xu F Y, Hou W, Xiong X Y, et al. The status and development strategy of coalbed methane industry in China[J]. Petroleum Exploration and Development, 2023, 50(4): 669−682. Google Scholar
[2]	接铭训. 鄂尔多斯盆地东缘煤层气勘探开发前景[J]. 天然气工业, 2010, 30(6): 1−6,121. Google Scholar Jie M X. Prospects in coalbed methane gas exploration and production in the Eastern Ordos Basin[J]. Natural Gas Industry, 2010, 30(6): 1−6,121. Google Scholar
[3]	李增学, 王明镇, 余继峰, 等. 鄂尔多斯盆地晚古生代含煤地层层序地层与海侵成煤特点[J]. 沉积学报, 2006, 24(6): 834−840. doi: 10.3969/j.issn.1000-0550.2006.06.008 CrossRef Google Scholar Li Z X, Wang M Z, Yu J F, et al. Sequence stratigraphy of late Paleozoic coal-bearing measures and the transgressive coal-formed features in Ordos Basin[J]. Acta Sedimentologica Sinica, 2006, 24(6): 834−840. doi: 10.3969/j.issn.1000-0550.2006.06.008 CrossRef Google Scholar
[4]	魏若飞, 信凯. 鄂尔多斯盆地东缘石西区块煤层气及致密砂岩气资源潜力评价[J]. 中国煤炭地质, 2022, 34(7): 7−11,38. doi: 10.3969/j.issn.1674-1803.2022.07.02 CrossRef Google Scholar Wei R F, Xin K. CBM and compact sandstone gas resources potential assessment in Shixi Block, Ordos Basin eastern margin[J]. Coal Geology of China, 2022, 34(7): 7−11,38. doi: 10.3969/j.issn.1674-1803.2022.07.02 CrossRef Google Scholar
[5]	康宇博. 石西区块煤系气水分布模式及可动性研究[D]. 北京: 中国矿业大学(北京), 2022: 35-71. Google Scholar Kang Y B. Research on distribution pattern and mobility of coal measures gas and water in Shixi Block[D]. Beijing: China University of Mining and Technology (Beijing), 2022: 35-71. Google Scholar
[6]	刘超, 孙蓓蕾, 曾凡桂, 等. 鄂尔多斯盆地东缘石西区块含氦天然气的发现及成因初探[J]. 煤炭学报, 2021, 46(4): 1280−1287. Google Scholar Liu C, Sun B L, Zeng F G, et al. Discovery and origin of helium-rich gas on the Shixi area, eastern margin of the Ordos Basin[J]. Journal of China Coal Society, 2021, 46(4): 1280−1287. Google Scholar
[7]	李家宏. 河东煤田中南部煤系页岩气与煤层气成藏特征对比研究[D]. 北京: 中国矿业大学(北京), 2016: 28-44. Google Scholar Li J H. Contrast of the reservoir forming characteristics between shale gas and coalbed methane in coal measure, Central and Southern Hedong Coalfield[D]. Beijing: China University of Mining and Technology (Beijing), 2016: 28-44. Google Scholar
[8]	Meng Y, Tang D, Xu H, et al. Geological controls and coalbed methane production potential evaluation: A case study in Liulin area, Eastern Ordos Basin, China[J]. Journal of Natural Gas Science and Engineering, 2014, 21: 95−111. doi: 10.1016/j.jngse.2014.07.034 CrossRef Google Scholar
[9]	陈世悦. 论秦岭碰撞造山作用对华北石炭二叠纪海侵过程的控制[J]. 岩相古地理, 1998, 18(2): 48−54. Google Scholar Chen S Y. The controls of the collisional orogenesis in the Qinling Mountains on the Carboniferous—Permian transgressional processes in North China[J]. Sedimentary Facies and Palaeogeography, 1998, 18(2): 48−54. Google Scholar
[10]	Yan M, Chi Q, Gu T, et al. Chemical composition of upper crust in Eastern China[J]. Science in China Series D: Earth Sciences, 1997, 40: 530−593. doi: 10.1007/BF02877620 CrossRef Google Scholar
[11]	Nesbitt H, Young G. Early Proterozoic climates and plate motions inferred from major element chemistry of lutites[J]. Nature, 1982, 299: 715−717. doi: 10.1038/299715a0 CrossRef Google Scholar
[12]	Bhatia M, Crook K. Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins[J]. Contributions to Mineralogy and Petrology, 1986, 92(2): 181−193. doi: 10.1007/BF00375292 CrossRef Google Scholar
[13]	Boynton W. Cosmochemistry of the rare earth elements: Meteorite studies[J]. Developments in Geochemistry, 1984, 2: 63−114. Google Scholar
[14]	杨晋东, 赵峰华, 秦胜飞, 等. 华北克拉通北缘中元古界杨庄组碳酸盐岩地球化学特征及其地质意义[J]. 天然气地球科学, 2020, 31(2): 268−281. Google Scholar Yang J D, Zhao F H, Qin S F, et al. Geochemical characteristics and geological significance of carbonate rocks in the middle Mesoproterozoic Yangzhuang Formation of northern margin of North China Craton[J]. Natural Gas Geoscience, 2020, 31(2): 268−281. Google Scholar
[15]	邹雨. 华北和扬子陆块中新元古代化学地层对比及意义[D]. 北京: 中国矿业大学(北京), 2020: 36-43. Google Scholar Zou Y. Meso—Neoproterozoic chemostratigraphic correlation and significance in North China and Yangtze Block[D]. Beijing: China University of Mining and Technology (Beijing), 2020: 36-43. Google Scholar
[16]	刘振庄, 白名岗, 杨玉茹, 等. 龙马溪组页岩不同显微形态有机质成因及其勘探潜力探讨[J]. 岩矿测试, 2020, 39(2): 199−207. Google Scholar Liu Z Z, Bai M G, Yang Y R, et al. Discussion on the genesis and exploration potential of different microscopic forms of organic matters in the Longmaxi Formation shale[J]. Rock and Mineral Analysis, 2020, 39(2): 199−207. Google Scholar
[17]	师展, 赵靖舟, 孙雄伟, 等. 鄂尔多斯盆地东南部上古生界煤系烃源岩特征及生烃潜力评价[J/OL]. 天然气地球科学. [2023-05-20].https://kns.cnki.net/kcms2/detail/62.1177.TE.20230615.1811.002.html. Google Scholar Shi Z, Zhao J Z, Sun X W, et al. Characteristics and hydrocarbon generation potential of upper Paleozoic coal measure source rocks in the southeast of Ordos Basin[J/OL]. [2023-05-20].https://kns.cnki.net/kcms2/detail/62.1177.TE.20230615.1811.002.html. Google Scholar
[18]	Lu J, Shao L Y, Sun B, et al. Sequence-paleogeography and coal accumulation of Carboniferous—Permian coal measures in the Eastern Ordos Basin[J]. Journal of China Coal Society, 2012, 37: 747−754. Google Scholar
[19]	汤艳杰, 贾建业, 谢先德. 粘土矿物的环境意义[J]. 地学前缘, 2002, 9(2): 337−344. Google Scholar Tang Y J, Jia J Y, Xie X D. Environment significance of clay minerals[J]. Earth Science Frontiers, 2002, 9(2): 337−344. Google Scholar
[20]	Meng Q, Liu Z, Bruch A A, et al. Palaeoclimatic evolution during Eocene and its influence on oil shale mineralisation, Fushun Basin, China[J]. Journal of Asian Earth Sciences, 2012, 45: 95−105. doi: 10.1016/j.jseaes.2011.09.021 CrossRef Google Scholar
[21]	谢小敏, 李利, 袁秋云, 等. 应用TIMA分析技术研究Alum页岩有机质和黄铁矿粒度分布及沉积环境特征[J]. 岩矿测试, 2021, 40(1): 50−60. Google Scholar Xie X M, Li L, Yuan Q Y, et al. Grain size distribution of organic matter and pyrite in Alum shales characterized by TIMA and its paleo-environmental significance[J]. Rock and Mineral Analysis, 2021, 40(1): 50−60. Google Scholar
[22]	何伟, 吴亮, 魏向成, 等. 宁东煤田中侏罗统延安组稀有稀散稀土元素地球化学特征及其对沉积环境的指示意义[J]. 岩矿测试, 2022, 41(6): 962−977. Google Scholar He W, Wu L, Wei X C, et al. Geochemical characteristics of rare, dispersed, and rare earth elements in the middle Jurassic Yan’an Formation of the Ningdong Coalfield and their indication for a sedimentary environment[J]. Rock and Mineral Analysis, 2022, 41(6): 962−977. Google Scholar
[23]	Meyer E, Quicksall A, Landis J, et al. Trace and rare earth elemental investigation of a Sturtian cap carbonate, Pocatello, Idaho: Evidence for ocean redox conditions before and during carbonate deposition[J]. Precambrian Research, 2013, 192(1): 89−106. Google Scholar
[24]	Maslov A, Podkovyrov V. Ocean redox state at 2500-500Ma: Modern concepts[J]. Lithology and Mineral Resources, 2018, 53: 190−211. doi: 10.1134/S0024490218030057 CrossRef Google Scholar
[25]	Sahoo S, Planavsky N, Jiang G, et al. Oceanic oxygenation events in the anoxic Ediacaran Ocean[J]. Geobiology, 2016, 14: 457−468. doi: 10.1111/gbi.12182 CrossRef Google Scholar
[26]	解兴伟, 袁华茂, 宋金明, 等. 海洋沉积物中氧化还原敏感元素对水体环境缺氧状况的指示作用[J]. 地质论评, 2019, 65(3): 671−688. Google Scholar Xie X W, Yuan H M, Song J M, et al. Indication of redox sensitive elements in marine sediments on anoxic condition of water environment[J]. Geological Review, 2019, 65(3): 671−688. Google Scholar
[27]	韦恒叶. 古海洋生产力与氧化还原指标——元素地球化学综述[J]. 沉积与特提斯地质, 2012, 32(2): 76−88. doi: 10.3969/j.issn.1009-3850.2012.02.012 CrossRef Google Scholar Wei H Y. Productivity and redox proxies of palaeo-oceans: An overview of elementary geochemistry[J]. Sedimentary Geology and Tethyan Geology, 2012, 32(2): 76−88. doi: 10.3969/j.issn.1009-3850.2012.02.012 CrossRef Google Scholar
[28]	Rimmer S. Geochemical paleoredox indicators in Devonian—Mississippian black shales, Central Appalachian Basin (USA)[J]. Chemical Geology, 2004, 206(3-4): 373−391. doi: 10.1016/j.chemgeo.2003.12.029 CrossRef Google Scholar
[29]	孙彩蓉. 鄂尔多斯盆地东缘石炭—二叠系页岩沉积相及微量元素地球化学研究[D]. 北京: 中国地质大学(北京), 2017: 17-23. Google Scholar Sun C R. Study on sedimentary facies and geochemistry of trace elements of Carboniferous—Permian shale in the Eastern Ordos Basin[D]. Beijing: China University of Geosciences (Beijing), 2017: 17-23. Google Scholar
[30]	Panahi A, Young G. A geochemical investigation into the provenance of the Neoproterozoic Port Askaig Tillite, Dalradian Supergroup, Western Scotland[J]. Precambrian Research, 1997, 85: 81−96. doi: 10.1016/S0301-9268(97)00033-8 CrossRef Google Scholar
[31]	McLennan S. Geochemical approaches to sedimentation, provenance, and tectonics[M]//Johnson M J, Basu A. Processes controlling the composition of clastic sediments. Geological Society of America, 1993: 21-40. Google Scholar
[32]	李绪龙, 张霞, 林春明, 等. 常用化学风化指标综述: 应用与展望[J]. 高校地质学报, 2022, 28(1): 51−63. Google Scholar Li X L, Zhang X, Lin C M, et al. Overview of the application and prospect of common chemical weathering indices[J]. Geological Journal of China Universities, 2022, 28(1): 51−63. Google Scholar
[33]	Young G, Wayne N. Paleoclimatology and provenance of the glaciogenic Gowganda Formation (Paleoproterozoic), Ontario, Canada: A chemostratigraphic approach[J]. Geological Society of America Bulletin, 1999, 111: 264−274. doi: 10.1130/0016-7606(1999)111<0264:PAPOTG>2.3.CO;2 CrossRef Google Scholar
[34]	杨海欧, 王长城, 李文杰, 等. 基于微量元素比值分析方法研究川东南地区小河坝组沉积环境和古气候环境[J]. 岩矿测试, 2017, 36(3): 289−296. Google Scholar Yang H O, Wang C C, Li W J, et al. Research on the sedimentary and paleoclimate environment of the Xiaoheba Formation in Southeastern Sichuan based on the trace elements ratio method[J]. Rock and Mineral Analysis, 2017, 36(3): 289−296. Google Scholar
[35]	熊小辉, 肖加飞. 沉积环境的地球化学示踪[J]. 地球与环境, 2011, 39(3): 405−414. Google Scholar Xiong X H, Xiao J F. Geochemical indicators of sedimentary environments—A summary[J]. Earth and Environment, 2011, 39(3): 405−414. Google Scholar
[36]	陈代钊, 汪建国, 严德天, 等. 扬子地区古生代主要烃源岩有机质富集的环境动力学机制与差异[J]. 地质科学, 2011, 46(1): 5−26. doi: 10.3969/j.issn.0563-5020.2011.01.003 CrossRef Google Scholar Chen D Z, Wang J G, Yan D T, et al. Environmental dynamics of organic accumulation for the principal Paleozoic source rocks on Yangtze Block[J]. Chinese Journal of Geology, 2011, 46(1): 5−26. doi: 10.3969/j.issn.0563-5020.2011.01.003 CrossRef Google Scholar
[37]	陈文彬. 西藏羌塘盆地上三叠统烃源岩有机地球化学特征[D]. 成都: 成都理工大学, 2012: 14-21. Google Scholar Chen W B. Geochemistry characterics of late-Triassic source rocks in Qiangtang Basin, Qinghai—Tibet Plateau[D]. Chengdu: Chengdu University of Technology, 2012: 14-21. Google Scholar
[38]	方朝刚, 章诚诚, 林洪, 等. 下扬子西南部前渊带晚奥陶世—早志留世黑色页岩沉积环境与有机质富集机理——以WDD1井为例[J]. 地球科学与环境学报, 2022, 44(2): 312−326. Google Scholar Fang C G, Zhang C C, Lin H, et al. Sedimentary environment and genesis organic matter enrichment of late Ordovician—early Silurian black shale in the fore deep zone, the Southwestern lower Yangtze Basin, China[J]. Journal of Earth Science and Environment, 2022, 44(2): 312−326. Google Scholar
[39]	夏鹏, 付勇, 杨镇, 等. 黔北镇远牛蹄塘组黑色页岩沉积环境与有机质富集关系[J]. 地质学报, 2020, 94(3): 947−956. Google Scholar Xia P, Fu Y, Yang Z, et al. The relationship between sedimentary environment and organic matter accumulation in the Niutitang black shale in Zhenyuan, Northern Guizhou[J]. Acta Geologica Sinica, 2020, 94(3): 947−956. Google Scholar
[40]	张慧芳, 吴欣松, 王斌, 等. 陆相湖盆沉积有机质富集机理研究进展[J]. 沉积学报, 2016, 34(3): 464−477. Google Scholar Zhang H F, Wu X S, Wang B, et al. Research progress of the enrichment mechanism of sedimentary organics in Lacustrine Basin[J]. Acta Sedimentologica Sinica, 2016, 34(3): 464−477. Google Scholar
[41]	李晓霞, 谷渊涛, 万泉, 等. 泥页岩中有机质-黏土复合体的微观结构、变形作用及源-储意义[J]. 石油与天然气地质, 2023, 44(2): 452−467. Google Scholar Li X X, Gu Y T, Wan Q, et al. Micro-architecture, deformation and source-reservoir significance of organic-clay composites in shale[J]. Oil and Gas Geology, 2023, 44(2): 452−467. Google Scholar
[42]	杜贵超, 杨兆林, 尹洪荣, 等. 鄂尔多斯盆地东南部长7₃段泥页岩储层有机质发育特征及富集模式[J]. 油气地质与采收率, 2022, 29(6): 1−11. Google Scholar Du G C, Yang Z L, Yin H R, et al. Developmental characteristics of organic matter and its enrichment model in shale reservoirs of Chang 7₃ Member in Yanchang Formation of Southeast Ordos Basin[J]. Petroleum Geology and Recovery Efficiency, 2022, 29(6): 1−11. Google Scholar
[43]	张洁. 鄂尔多斯盆地东部上古生界烃源岩评价[D]. 西安: 西安石油大学, 2012: 25-31. Google Scholar Zhang J. Source rock evaluation of the upper Palaeozoic in Eastern Ordos Basin[D]. Xi’an: Xi’an Shiyou University, 2012: 25-31. Google Scholar