西南石油大学学报(自然科学版) ›› 2020, Vol. 42 ›› Issue (2): 15-26.DOI: 10.11885/j.issn.1674-5086.2019.01.29.01

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Seismic Sedimentary Study on the Fan-delta of the Baikouquan Formation on the Western Slope of the Mahu Sag

LI Quan1,2, LI Peijun3, NI Zhen3, LIU Jun3, LIU Hechong3   

  1. 1. CNOOC International Limited, Chaoyang, Beijing 100028, China;
    2. Institute of Resources and Environment, Henan Polytechnic University, Jiaozuo, Henan 454003, China;
    3. Fengcheng Oilfield Operating Area, Xinjiang Oilfield Company, CNPC, Karamay, Xinjiang 834000, China
  • Received:2019-01-29 Online:2020-04-10 Published:2020-04-10

Abstract: Fan-delta front glutenite exhibits wide variation in physical properties, making it difficult to predict high-quality reservoirs. Aiming to address this key issue, we identified and described the sedimentary facies distribution characteristics and filling process of the fan-delta in Baikouquan Formation in the Fengnan region on the western slope of the Mahu Sag (Junggar Basin). The study was guided by seismic sedimentology theory, and was done by means of seismic lithology, seismic geomorphology, and stratigraphic slicing techniques with logging and seismic data. In this study, we first established a high-precision sequence stratigraphic framework of the Triassic Baikouquan Formation on the western slope of the Mahu Sag, and delineated six fourth-order sequences. Then, we identified the sedimentary microfacies of the diversion channels, river channels, fan-delta front subaqueous diversion channels, estuary dams, and sheeted sands, as well as the corresponding logging characteristics of the Baikouquan Formation in the study area. We also indicated the correspondence between reservoir sand bodies and seismic amplitude by lithology calibration. Finally, with the help of slicing techniques in a fourth-order sequence grid, we clarified the filling-evolution process of the fan-delta sedimentary system in the Baikouquan Formation and pointed out the distribution range of high-quality reservoirs in the fan-delta front and the consequent prospecting direction.

Key words: high-precision sequence grid, seismic sedimentology, stratigraphic slicing, filling evolution, seismic geomorphology

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