Oil & Gas Geology ›› 2009, Vol. 30 ›› Issue (1): 47-52,58.doi: 10.11743/ogg20090107

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Micropores from devitrification in volcanic rocks and their contribution to reservoirs

Zhao Hailing1,2,3, Huang Wei3,4, Wang Cheng3,4, Di Yongjun1,2,3, Qi Jingshun3,4, Xiao Yong3, Liu Jie4   

  1. 1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China;
    2. Key Laboratory of Lithosphere Tectonics and Litho-probing Technology, Ministry of Education, China University of Geosciences, Beijing 100083, China;
    3. School of Geosciences and Resources, China University of Geosciences, Beijing 100083, China;
    4. Exploration and Development Research Institute, Daqing Oilfield Limited Company, Daqing, Heilongjiang 163712, China
  • Received:2008-10-18 Online:2009-02-25 Published:2012-01-16

Abstract:

Petrography studies show that devitrification in volcanic rocks can produce a considerable number of micropores.The micropores observed in volcanic rocks are a complex of micropores from devitrification and that from interaction of minerals with fluids.In pyromerides and ignimbrites,micropores from devitrification are the second largest pore type after the vesicle,accounting for 20%and 30%of the total of all pore types in pyromerides and ignimbrites respectively.While in tuff,they are the predominant pore type and account for about 70%of the total pore spaces.The principles and methods of mass balance and the physical processes of devitrification can be used to estimate the micropores generated by devitrification of glass in pyromeride,ignimbrite and tuff.Calculation with the thermodynamical theories and methods of fluid-rock interaction shows that feldspar dissolution at least can produce pores of 20 cm3/mol.

Key words: pyromeride, ignimbrite, tuff, devitrification, micropore, volcanics

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