Oil & Gas Geology ›› 2013, Vol. 34 ›› Issue (5): 667-671.doi: 10.11743/ogg20130513

• Sequences and Reservoirs • Previous Articles     Next Articles

Oil accumulation patterns of Chang 4+5 and Chang 6 in Yan’an delta,Ordos Basin

Li Airong1,2, Wang Weixi3, Wu Fuli2, Zhao Jingzhou2, Zhang Hui2   

  1. 1. State Key Laboratory of Continental Dynamics, Northwest University, Xi'an, Shaanxi 710069, China;
    2. School of Earth Sciences and Engineering, Xi'an Shiyou University, Xi'an, Shaanxi 710065, China;
    3. Yangchang Petroleum (Group) Co. LTD, Yan'an, Shaanxi 716000, China
  • Received:2013-03-31 Revised:2013-08-22 Online:2013-10-08 Published:2013-10-08

Abstract:

Yan'an Delta is located in the southeastern part of Shanbei slope in Ordos Basin and contains several oil reservoirs.Chang 4+5 and Chang 6 are the main pay zones.According to sedimentary facies,reservoir-seal assemblage and distance from source,this paper established several hydrocarbon accumulation patterns.The superimposed channel sandbodies in the delta are the major migration pathways for the hydrocarbon,and they provided conditions for long distance lateral and vertical migration of hydrocarbons.According to the distance between source and reservoir and the ability of oil accumulation,the reservoirs can be divided into three types,i.e,proximal accumulation,distal accumulation and pro-ximal dissipation.The former two types of accumulation areas have better oil enrichment conditions as the hydrocarbon migration and/or sealing conditions are favorable,while the later is limited in hydrocarbon accumulation capacity despite its shortest distance to oil source due to the migration of hydrocarbons to structural high.According to the migration pathways'quality and reservoir location,the accumulation pattern of Yan'an Delta are divided into five types,i.e.the proximal accumulation pattern with main migration pathways,the distal accumulation pattern with main migration pathways,the proximal accumulation pattern with sub-migration pathways,the distal accumulation pattern with sub-migration pathways and the proximal dissipation pattern.

Key words: hydrocarbon migration, hydrocarbon accumulation pattern, Yan’an delta, Ordos Basin

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