China Petroleum Exploration ›› 2015, Vol. 20 ›› Issue (3): 22-29.

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Sedimentary Development Law of Permian Wutonggou Formation in Jimsar Sag of Junggar Basin

Ding Chao1, Wang Jiawei2   

  1. 1Fengcheng Operational Zone, PetroChina Xinjiang Oilfield Company
    2 School of Geosciences, China University of Petroleum (East China)
  • Online:2015-05-15 Published:2015-05-22
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Abstract:

Permian Wutonggou Formation in Jimsar Sag of Junggar Basin has a potential for upgrading of reserves and progressive expansion, but its distribution scope of favorable reservoirs and characteristics of vertical variation remained unclear. Wutonggou Formation is the stratigraphic record of Jimsar Sag deposited predominantly by the rising semi-cycle and subordinately by the falling semi-cycle during the intermediate base level cycle. The large-scale braided delta plain subfacies and frontal subfacies developed in the study area at the initially rising stage of the intermediate base level cycle. The lithologic characters are gray sandy conglomerates and gravel sandstone mainly in coarse grains with a medium to large thickness. The braided delta plain subfacies basically disappeared in the middle and later period of the intermediate base level cycle. The sedimentary scope of frontal facies dwindled gradually while the reservoir layers became thinner. The subfacies is mainly coarse and fine sandstone of medium to thick layers. The thin-layer fine sandstone and siltstone of shore to shallow lacustrine subfacies developed in the falling stage of the intermediate base level cycle. The reservoir rocks of Wutonggou Formation are classified into the types of II, III and IV according to the criteria of Permian rock in Junggar Basin. The reservoir quality of lower member of Wutonggou Formation is better than that of upper member. The favorable reservoir sand bodies are distributed in eastern slope zone, slope near-shore zone and northeast zone of Jimsar Sag.

 

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