CHARACTERS OF MICRO-STRUCTURE AND PERCOLATION IN TIGHT SANDSTONE GAS RESERVOIRS

With the dwindling ofconventional gas reservoirs, people are paying attention to theexploration and exploitation of tight sandstone gas reservoirs.However, few studies were directed to the mechanism of hightransfer fluid; the exploitation has been very limited. Tightsandstone gas reservoirs are characterized by extended spatialscales, including micro scale, natural fracture scale, andhydraulic fracture scale, and there will be multi-scale effects while gas is percolated through the tight sandstone. Gas transfer processesin the tight sandstone gas reservoirs consist of desorption,diffusion and percolation, including diffusion in theconcentration field and percolation in the pressure field. Thereview of this paper discusses the special characters of tightsandstone gas reservoirs, the descriptions and methodology. The range of gas transfer in tight sandstone is classified on the basisof Knudsen number. It is concluded that some fine descriptive methods should be established to describe tight sandstonemicro-structures and the study about tight sandstone gas transferin the condition of multi-scales should be carried out.