Oil & Gas Geology ›› 2015, Vol. 36 ›› Issue (1): 73-79.doi: 10.11743/ogg20150109

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Development characteristics and genetic mechanism of authigenic kaolinite in sandstone reservoirs of the Dongying Sag, Bohai Bay Basin

Zhang Yongwang1,2, Zeng Jianhui1,2, Qu Zhengyang2, Chen Junbing3   

  1. 1. State Key Laboratory of Petroleum Resource and Prospecting, China Lniversity of Petroleum Beijing 102249, China;
    2. College of Geosciences, China University of Petroleum, Beijing 102249, China;
    3. Hydrological and Engineering Geology Team of Zhejiang Province, Ningbo, Zhejiang 315010, China
  • Received:2014-08-05 Revised:2014-11-26 Online:2015-02-08 Published:2015-02-11

Abstract:

Arthroscopic characteristics, distribution and occurrence of kaolinite are analyzed through quantity thin section analysis, core observation, scanning electron microscope and X-ray powder diffraction.The results show that the kaolinite of sandstone reservoirs in Dongying Sag has two genetic types including authigenic kaolinite and terrigenous kaolinite.The authigenic kaolinites are common in the reservoirs.Microscopically, they show complete crystal form, and fill intergranular pores and dissolution pores of feldspar in typical sheet or vermicular shapes.The "spotted" filling feature of the authitgenic kaolinite aggregates are clear on cast thin sections.The terrigenous kaolinites are rare and often occur in shallow layers.They are formed in association with the non-clay minerals like clastic particles in deposition process.Based on the study mentioned above, the genetic mechanism of authigenic kaolinite is discussed.It is supposed that feldspar dissolution is the main material source for the formation of authigenic kaolinite.Sandstones with large grain size and well sorting have high content of kaolinite, indicating that, in addition to acid fluid environment and sufficient material supply, strong fluid dynamic is also an important controlling factor of authigenic kaolinite formation.

Key words: authigenic kaolinite, genesis of kaolinite, sandstone reservoir, Dongying Sag

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