Oil & Gas Geology ›› 2022, Vol. 43 ›› Issue (2): 456-466.doi: 10.11743/ogg20220217

• Methods and Technologies • Previous Articles     Next Articles

Raman spectroscopy of bitumen from the Sinian Dengying Formation reservoirs, Gaoshiti-Moxi area, central Sichuan Basin

Chunquan Li1,2(), Honghan Chen1,2, Xuewei Xiao1,2, Zecheng Wang3, Hua Jiang3   

  1. 1.Key Laboratory of Tectonics and Petroleum Resources,Ministry of Education·China University of Geosciences (Wuhan),Wuhan,Hubei 430074,China
    2.Department of Petroleum Geology,School of Earth Resources,China University of Geosciences (Wuhan),Wuhan,Hubei 430074,China
    3.Research Institute of Petroleum Exploration & Development,PetroChina,Beijing 100083,China
  • Received:2020-08-07 Revised:2022-01-20 Online:2022-04-01 Published:2022-03-11

Abstract:

As an effective technique to characterize the maturity of organic matter, Raman spectroscopy was employed to analyze bitumen in 21 samples from the Sinian Dengying Formation reservoirs in the Gaoshiti-Moxi area, central Sichuan Basin. The equivalent vitrinite reflectance values of the bitumen were calculated with empirical equations to determine the maturity stage of the bitumen and the thermal alternation of reservoirs sampled. The results indicate that most bitumen (81.1 %) filled dissolved pores and fractures are highly to over mature. The Raman spectrums change drastically near the equivalent vitrinite reflectance of 3.0 %, suggesting a two-section evolving trend. Anomalous high equivalent vitrinite reflectance values are typical responses of hot fluid activities, indicating thermal anomalies experienced by the reservoirs. The spatial distribution of the equivalent vitrinite reflectance values also points to the possibility of multiple thermal alteration, which may serve to confirm the assumption that gas is generated from oil cracking and to explain the distribution of current gas reservoirs in the area.

Key words: Raman spectroscopy, maturity, reservoir bitumen, Dengying Formation, Sinian, Gaoshiti-Moxi area, Sichuan Basin

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