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Classification and origin of natural gases from Lishui Sag, the East China Sea Basin

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Abstract

Natural gases discovered up to now in Lishui Sag, the East China Sea Basin, differ greatly in gaseous compositions, of which hydrocarbon gases amount to 2%–94% while non-hydrocarbon gases are dominated by CO2. Their hydrocarbon gases, without exception, contain less than 90% of methane and over 10% of C2 + heavier hydrocarbons, indicating a wet gas. Carbon isotopic analyses on these hydrocarbon gases showed that δ 13C1, δ 13C2 and δ 13C3 are basically lighter than −44‰, −29‰ and −26‰, respectively. The difference in carbon isotopic values between methane and ethane is great, suggesting a biogenic oil-type gas produced by the mixed organic matter at peak generation. δ 13 \( C_{CO_2 } \) values of nonhydrocarbon gases are all heavier than −10‰, indicating a typical abiogenic gas. The simulation experiment on hydrocarbon generation of organic matter in a closed gold-tube system showed that the proportion of methane in natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit is obviously higher than that in natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit, consequently the proportion of heavier hydrocarbons of the former is remarkably lower than that of the latter. Moreover, δ 13C1 values of natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit are about 5‰ heavier than those of natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit while δ 13C2 and δ 13C3 values of the former are over 9‰ heavier than those of the latter. Currently the LS36-1 oil-gas pool is the only commercial oil-gas reservoir in Lishui Sag, where carbon isotopic compositions of various hydrocarbon components differ greatly from those of natural gases produced by the Lingfeng Formation organic matter but are very similar to those of natural gases derived from the Yueguifeng Formation organic matter, therefore, natural gases in the LS36-1 oil-gas pool are mainly derived from the Yueguifeng Formation lacustrine source rock rather than the Lingfeng Formation marine or Mingyuefeng Formation coal-measures source rocks.

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References

  1. Huang Z L, Jiang L, Hao S S. Classification of gas genesis in Lishui Sag of East Sea Basin. Nat Gas Industry (in Chinese), 2003, 23(3): 29–31

    Google Scholar 

  2. Chen Z Y, Wu P K, Wu Z X. Petroleum geology and exploration potential of Lishui Sag. China Offshore Oil and Gas (Geology)(in Chinese), 2000, 14(6): 384–391

    Google Scholar 

  3. Jiang L, Li B H, Zhong S L, et al. Biostratigraphy and paleoenvironment of the Yueguifeng Formation in the Taipei Depression of the continental shelf basin of the East China Sea. Mar Geol Quat Geol (in Chinese), 2004, 24(1): 37–41

    Google Scholar 

  4. Chen J P, Liang D G, Zhang C J, et al. A study on characteristics and hydrocarbon-generative potential of source rocks in Lishui-Jiaojiang Depression. Res Report (in Chinese), 2005, 1–208

  5. Ge H P, Chen Z Y, Fang L F, et al. A discussion on hydrocarbon accumulation periods in Lishui Sag, East China Sea Basin. China Offshore Oil and Gas (Geology) (in Chinese), 2003, 17(1): 44–50

    Google Scholar 

  6. Sun Y M, Xi X Y. Petroleum reservoir filling history and oil-source correlation in the Lishui Sag, East China Sea Basin. Petrol Explor Develop (in Chinese), 2003, 30(6): 24–28

    Google Scholar 

  7. Guo Y H, Yu S, Ge L. Formation of the LS36-1 oil and gas structure in the Lishui Sag, East China Sea Basin. Petrol Explor Develop (in Chinese), 2003, 30(6): 29–31

    Google Scholar 

  8. Jia C Y, Xia B, Wang H, et al. Characteristic of tectonic evolution and petroleum geology in Lishui Sag, East China Sea Basin. Nat Gas Geosci (in Chinese), 2006, 17(3): 397–401

    Google Scholar 

  9. Compiling Group for Records of Petroleum Geology in Coastal Offshore and Adjacent Oil-gas Sea Areas. Records of Petroleum Geology in China (16). Beijing: Petroleum Industry Press, 1990

    Google Scholar 

  10. Yang Y Q, Tian H, Jiang L, et al. Late Paleocene sea-level fluctuations and prediction of favourable reservoirs in Lishui Sag, East China Sea Basin. China Offshore Oil and Gas (Geology) (in Chinese), 2003, 17(1): 69–73

    Google Scholar 

  11. Huang Z L, Liu G D, Hao S S, et al. A systematical research on the petroleum system in Lishui-Jiaojiang Depression, East Sea Offshore Basin. Research Report by Institute of Geology, East Sea Division, CNOOC, 1998

  12. Jiang L, Wang Y, Jin Q. Petroleum system and oil expolration in the west Lishui sag, the East China Sea Basin. Petrol Geol Exp (in Chinese), 2001, 23(4): 368–389

    Google Scholar 

  13. Liu J Z, Xiang T S. Collection, quantitative analysis and carbon isotopic analysis methods of minor/trace hydrocarbon gases. Petrol Geol Exp (in Chinese), 2003, 25(5): 492–497

    Google Scholar 

  14. Ye J, Guo D X. Geochemical characters of the natural gas in West Lake Depression, the East China Sea. Exp Petrol Geol (in Chinese), 1996, 18(2): 174–181

    Google Scholar 

  15. Jia J Y, Xu X H, Sun B Q. Oil/Gas geochemical character in the Xihu Trough of the East China Sea. Offshore Oil (in Chinese), 2000, 2: 1–7

    Google Scholar 

  16. Fu N, Li Y C, Liu D, et al. Geochemical characteristics of natural gas migration in Pinghu gas field, East China Sea. Petrol Explor Develop (in Chinese), 2005, 32(5): 34–37

    Google Scholar 

  17. Dai J X, Pei X G, Qi H F, et al. Natural Gas Geology in China (Vol. I) (in Chinese), Beijing: Petroleum Industry Publishing House, 1992

    Google Scholar 

  18. Jiang Z S, Luo X, Li Z S, et al. Carbon isotope composition of benzene and toluene as a new index for correlation of gases with their source rocks. Geochimica (in Chinese), 2000, 29(4): 410–415

    Google Scholar 

  19. Cramer B, Faber E, Gerling P, et al. Reaction kinetics of stable carbon isotopes in natural gas insights from dry, open system pyrolysis experiments. Energy Fuels, 2001, 15: 517–532

    Article  Google Scholar 

  20. Cramer B. Methane generation from coal during open system pyrolysis investigated by isotope specific, Gaussian distributed reaction kinetics. Org Geochem, 2004, 35: 379–392

    Article  Google Scholar 

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Correspondence to JianPing Chen.

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Supported by the Research Project of CNOOC (Grant No. CT/04-EXP-009)

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Chen, J., Ge, H., Chen, X. et al. Classification and origin of natural gases from Lishui Sag, the East China Sea Basin. Sci. China Ser. D-Earth Sci. 51 (Suppl 1), 122–130 (2008). https://doi.org/10.1007/s11430-008-5001-5

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  • DOI: https://doi.org/10.1007/s11430-008-5001-5

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