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Geoscience ›› 2018, Vol. 32 ›› Issue (05): 985-994.DOI: 10.19657/j.geoscience.1000-8527.2018.05.11

• Study of Natural Gas Hydrates • Previous Articles     Next Articles

Geological Characteristics of Carboniferous-Jurassic Potential Source Rocks for Natural Gas Hydrates in Muli Depression, South Qilian Basin

FAN Dongwen1,2(), LU Zhenquan2(), XIAO Rui2, NIU Suoan3, QI Lajia3, WEI Yi3, ZHANG Yong’an3, FEI Deliang3, DANG Xiaofeng3   

  1. 1. School of Energy Resources, China University of Geosciences, Beijing 100083, China
    2. Oil & Gas Survey, China Geological Survey, Beijing 100029, China
    3. Qinghai No.105 Coal Geological Exploration Team, Xining, Qinghai 810007, China
  • Received:2018-04-10 Revised:2018-09-02 Online:2018-10-10 Published:2018-11-04

Abstract:

Through field geological survey and lab-based analyses on the Carboniferous to Jurassic sedimentary sequences along five geological sections in the Muli depression of south Qilian basin, we clarify the regional lithological characteristics, sedimentary facies and sedimentary evolution. The Carboniferous-Permian sedimentation system is characterized by medium-thick sandstone with thin mudstone interbeds, and comprises shallow marine continental shelf, littoral and delta facies. The fault development likely reduced the partial strata thickness and the mudstone sequence is mostly lost, making it an unlikely potential source rock of gas hydrates. The Upper Triassic sedimentation system is characterized by the development of medium-thick sandstone with medium-thin mudstone interbeds, and comprises tidal flat, lacustrine and fluvial facies. The mudstone sequence is thick, making it the main potential source rock of gas hydrates. The Middle Jurassic sedimentation system is mainly characterized by thick mudstone with sandstone, and comprises braided river, delta and lacustrine facies, making it a potential source rock of gas hydrates. Our finding provides important implications on gas hydrate source rocks in the Muli depression.

Key words: south Qilian basin, Muli depression, gas hydrate, gas source rock, sedimentary facies analysis

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