Oil & Gas Geology ›› 2009, Vol. 30 ›› Issue (3): 330-336,349.doi: 10.11743/ogg20090312

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Accumulation mechanism of low-abundance oil reservoirs in the Yanchang Formation of Shuguang oilfield,the Ordos Basin

Zhou Wen1, Su Fuyi2, Dai Jianwen1   

  1. 1. State Key Laboratory of Reservoir Geology and Development Engineering, Chengdu University of Technology, Chengdu, Sichuan 610059, China;
    2. Research Institute of SINOPEC North China Company;Zhengzhou, Henan 450006, China
  • Received:2008-09-26 Online:2009-06-25 Published:2012-01-16

Abstract:

The mechanism of oil-gas migration of the exceptionally low-abundance oil reservoirs in the Yanchang Formation of the Shuguang oilfield,Ordos basin,is analyzed in this paper by applying the theory of secondary hydrocarbon migration.The results show that the major source rocks of the Chang-7 member(the 7th member of the Yanchang Formation) had generated and expelled large amount of hydrocarbons during the mid-late Yenshanian(Cretaceous),and the Chang-6 and Chang-8 sandbodies acted as carriers beds for hydrocarbon migration.During the migration process,small amount of hydrocarbon was 'left behind' because of local barriers formed by physical property contrast and lithology changes,and formed the so-called low-abundance oil reservoirs inside the migration-discharge zone.This kind of reservoir is one of the most important reservoirs that deserve much more attention not only in Ordos Basin but also in other large basins in China.It shall be regarded as an important target for future hydrocarbon exploration.

Key words: migration-discharge face, conceptual accumulation model, low-abundance oil reservoir, Yanchang Formation, Shuguang area, Ordos Basin

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