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Abstract Pores and fractures are two main flow channels in fractured porous media. Under low and ultra-low permeability conditions，whether seepage occurs in media or not is decided by whether pores and fractures can form a penetrated channel or not. A dual-percolation model coupled the pore percolation theory and the fracture percolation theory is presented to study the conductivity of the low and ultra-low fractured porous media. Based on the presented dual-percolation model，two parameters and D are presented to reflect and compare the conductivities of fractured porous media；and the physical meaning of these two parameters is quantitatively discussed. The connectivity of low and ultra-low permeability fractured porous media is investigated based on these two parameters. It is shown that the low and ultra-low permeability fractured porous media can be generally divided into three types by taking as the critical value，i.e. dispersion type，critical type，and directional type. Media are self-sealing when and they can be named as directional type. However，with the enhancements of randomnesses of porous connectivity and fracture directions，the self-sealing tendency will be destroyed and the conductivity will increase，which causes the media tending to become dissipation type. A few long fractures can play a great role on the connectivity of media.
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Received: 25 June 2010
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2011, Vol. 30 
