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Geoscience ›› 2024, Vol. 38 ›› Issue (05): 1291-1305.DOI: 10.19657/j.geoscience.1000-8527.2023.108

• Oil and Gas Exploration in Sedimentary Basin and Key Techniques • Previous Articles     Next Articles

Characteristics and Modeling of Saline Lake Gravity Flow Deposition in the Qianjiang Formation, Northern Qianjiang Depression, Jianghan Basin

BAO Hanyong1(), GUO Libin1(), GE Taoyuan2, JIANG Zaixing2   

  1. 1. Jianghan Oilfield Company, SINOPEC, Wuhan, Hubei 430223, China
    2. School of Energy Resources, China University of Geosciences (Beijing), Beijing 100083, China
  • Online:2024-10-10 Published:2024-11-13
  • Contact: GUO Libin

Abstract:

Large-scale gravity flow deposits were first doscovered in the saline lake deposits of the Qianjiang Formation within the Qianjiang Depression. Their depositional characteristics, diagenetic mechanisms, main controlling factors, and favorable lithofacies require further investigation. Through petrographic observations of 20 core wells, combined with logging data, thin sections, mineralogical composition, and grain size analysis, ten gravity flow-related lithofacies were identified. The gravity flow deposits can be classified into four genetic facies: storm gravity flow, sliding-slumping, debris flow, and turbidity flow deposits. Based on lithofacies associations, the gravity flow deposits can be further subdivided into proximal, middle, and distal deposits. During the sedimentation of Mbr40, the climate was dry, and the secondary fracture zone in the Tankou area was active, leading to sliding and slumping. During the sedimentation of Mbr40M, the climate was relatively humid, and flooding triggered the long-distance transport of hyperconcentrated flows. Pure massive siltstones and fine sandstones from clastic flows, as well as parallel laminated sandstones from turbidity flows, are favorable reservoir rocks. The combination of parallel laminated siltstone, massive siltstone, and mudstone is the dominant lithofacies associations formed during fluid transformation.

Key words: saline lake gravity flow, sedimentary characteristics, depositional model, Qianjiang Depression, Qianjiang Formation

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