Abstract
Coalbed methane (CBM) accumulation models include continuous gas accumulation and staged gas accumulation. However, studied on the geochemical characteristics and indices to evaluate staged accumulation CBM are lacking. This study for the first time obtained the carbon and hydrogen isotopic compositions of methane and ethane generated at different evolution stages using thermal simulation of samples prepared by treating an herbaceous swamp peat at different temperatures. The results showed that the carbon isotopic compositions of methane and ethane were obviously affected by the thermal evolution level of the starting sample, while the hydrogen isotopic compositions were closely related to the maturity of gases. The carbon and hydrogen isotopic compositions of gases generated by coal-forming organic matter with R o values from 1.2%, 1.7%, 2.4%, 3.2% and 3.7% to 5.2% were determinated. The relationship between R o values and the carbon and hydrogen isotopic compositions of gases generated by coal-forming organic matter at different evolution stages as well as the carbon or hydrogen isotopic relationships between methane and ethane were established. The results provide a scientific basis for studying the genesis of CBM generated at different maturity intervals and understanding the geochemical characteristics of staged accumulation CBM. These results were applied to a case study on CBM from the southern Qinshui basin, and it was found that the CBM accumulated after the Middle Jurassic and was characteristic of staged gas accumulation. This is consistent with the result of geological studies, and further showed that the results of thermal simulation experiments are very important for evaluating the genesis of natural CBM.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Clayton J L. Geochemistry of coalbed gas-A review. Int J Coal Geol, 1998, 35: 159–173
Kotarba M J. Isotopic geochemistry and habitat of the natural gases from the Upper Carboniferous Zacier coal-bearing Formation in the Nowa Ruda coal district (Lower Silesia, Poland). Org Geochem, 1990, 16: 549–560
Liu D M, Yang Q, Tang D Z. Reaction kinetics of coalification in Ordos Basin, China. In: Yang Q, ed. Geology Fossil Fuels-coal. Utrecht: The Netherlands, 1997. 147–159
Qin Y, Tang X Y, Ye J P, et al. Characteristics and originals of stable carbon isotope in coalbed methane of China (in Chinese). J Chin Univ Mining Tech, 2000, 29: 113–119
Kotarba M J, Rice D D. Composition and origin of coalbed gases in the Lower Silesian basin, southwest Poland. Appl Geochem, 2001, 16: 895–910
Zhao M J, Song Y, Su X B, et al. The key stage and moment of coalbed gas reservoir evolution in the Qinshui basin, China. Chinese Sci Bull, 2005, 50: 110–110
Landais P. Assessement of coal potential evolution by experimental simulation of natural coalification. Org Geochem, 1991, 17: 705–710
Raymond M, Landais P. Artificial coalification: Comparison of confined pyrolysis and hydrous pyrolysis. Fuel, 1994, 73: 1691–1696
Behar F, Vandenbroucke M, Teermann S C, et al. Experimental simulation of gas generation from coals and a marine kerogen. Chem Geol, 1995, 126: 247–260
Cramer B. Methane generation from coal during open system pyrolysis investigate by isotope specific, Gaussian distributed reaction kinetics. Org Geochem, 2004, 35: 379–392
Duan Y, Wu B X, Zheng C Y, et al. Studies on thermal simulation of the formation and evolution of coalbed gas. Chinese Sci Bull, 2005, 50: 40–44
Duan Y, Wu B X, Zheng C Y, et al. Studies on kinetics of hydrocarbon generation from coals in Qinshui basin. Chinese Sci Bull, 2005, 50: 1904–1911
Liu Q Y, Liu W H, Dai J X. Characterization of pyrolysates from maceral components of Tarim coals in closed system experiments and implications to natural gas generation. Org Geochem, 2007, 38: 921–934
Chen J P, Deng C P, Wang H T, et al. Biomarker and its implication of pyrolysis oils of macerals from Jurassic coal measures, northwest China (in Chinese). Geochimica, 2006, 2: 141–150
Behar F, Vandenbroucke M, Teerman S C, et al. Experimental simulation of gas generation from coals and a marine kerogen. Chem Geol, 1995, 126: 247–260
Liu Q Y, Liu W H, Qin S F, et al. Geochemical study of thermal simulation on coal and coal with different mediums-Yielding rate of gaseous and organic liquid products and their evolution (in Chinese). Acta Sediment Olog Sin, 2001, 19: 465–468
Yao S, Xue C, Hu W, et al. A comparative study of experimental maturation of peat, brown coal and subbituminous coal: Implications for coalification. Int J Coal Geol, 2006, 66: 108–118
Rollins M S, Cohen A D, Bailey A M, et al. Organic chemical and petrographic changes induced by early-stage artificial coalification of peats. Org Geochem, 1991, 17: 451–465
Kracht O, Gleixner G. Isotope analysis of pyrolysis products from Sphagnum peat and dissolved organic matter from bog water. Org Geochem, 2000, 31: 645–654
Stach E, Mackowsky M-Th, Teichmüller M, et al. Stach’s Textbook of Coal Petrology. 2nd ed. Berlin: Gebrüder Borntraeger, 1982
Stahl J W, Carey B D. Source-rock identification by isotope analyses of natural gases from fields in the Val Verde and Delaware Basins, West Texas. Chem Geol, 1975, 16: 257–267
Dai J X, Qi H F. δ 13C-R o relationship of China’s coalbed gas (in Chinese). Chinese Sci Bull, 1989, 34: 690–692
Duan Y, Sun T, Liu J F, et al. Thermal simulation experiment and application of staged evolution of coalbed methane carbon isotope (in Chinese). Acta Sediment Sin, 2010, 28: 401–404
Sun Z X, Zhang W, Hu B Q, et al. Geothermal field and its relation with coalbed methane distribution of the Qinshui basin. Chinese Sci Bull, 2005, 50: 93
Sang S X, Liu H J, Li G Z, et al. Generation and enrichment of coal bed methane I. Gasyield in effective stage and concentration of coal bed methane (in Chinese). Coal Geol Explor, 1997, 25: 14–17
Zhao M J, Song Y, Su X B, et al. Key geological time of deciding the geochemical characteristics of coal bed methane (in Chinese). Nat Gas Ind, 2005, 25: 51–54
Author information
Authors and Affiliations
Corresponding author
Additional information
This article is published with open access at Springerlink.com
Rights and permissions
This article is published under an open access license. Please check the 'Copyright Information' section either on this page or in the PDF for details of this license and what re-use is permitted. If your intended use exceeds what is permitted by the license or if you are unable to locate the licence and re-use information, please contact the Rights and Permissions team.
About this article
Cite this article
Duan, Y., Zhang, X., Sun, T. et al. Carbon and hydrogen isotopic compositions and their evolutions of gases generated by herbaceous swamp peat at different thermal maturity stages. Chin. Sci. Bull. 56, 1383–1389 (2011). https://doi.org/10.1007/s11434-011-4356-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11434-011-4356-8