Oil & Gas Geology ›› 2013, Vol. 34 ›› Issue (5): 679-684.doi: 10.11743/ogg20130515

• Sequences and Reservoirs • Previous Articles     Next Articles

Characteristics of the Chang 8 tight sandstone reservoirs and their genesis in Huaqing area,Ordos Basin

Zhang Jizhi1, Chen Shijia1, Xiao Yan2, Lu Jungang1, Yang Guping3, Tang Haiping1, Liu Chaowei1   

  1. 1. Southwest Petroleum University, Chengdu, Sichuan 610500, China;
    2. Engineering Investigation and Design Institute of Sichuan Provincial Coalfield Bureau, Chengdu, Sichuan 610500, China;
    3. Chang qing Oil Field Company, PetroChina, Xi'an, Shaanxi 710000, China
  • Received:2012-07-30 Revised:2013-08-26 Online:2013-10-08 Published:2013-10-08

Abstract:

Chang 8 sandstone of the Upper Triassic Yanchang Formation in Huaqing area,Ordos Basin,is a typical set of reservoirs with low-ultra low porosity and permeability.Its average porosity is 8.27% and average permeability is 0.51×10-3 μm2.The main type of pore space is residual inter-granular pore,and the main type of pore structure is tiny and micro throat.The Chang 8 reservoir has experienced complex diagenesis,such as compaction,cementation,and dissolution.The destructive diagenesis of compaction and cementation sharply reduce the primary pores of the reservoir,besides,some pores are filled with bitumen,resulting in the lowering of porosity and permeability and the tightness of the reservoir.Diagenis is a determining factor in reservoir tightening,while depositional environment is the basic controlling factor of the reservoir physical property.The underwater distributary channel sands in delta front have the best physical property,and the central part of the sandbody is better than its two sides.With the increasing of interstilital matter,the physical properties get poorer.

Key words: reservoir bitumen, interstitial matter, mineralogical composition, diagenesis, sedimentation, tight sandstone, Ordos Basin

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