Abstract: There are many misunderstandings of low permeability reservoir,which is due to incorrect experiment methods and shortage of rational research.Some microfractures develope in low permeability reservoir,their openings are narrow and continuity are poor and under stress（open fractures can not exist underground）they are closed,so permeability is quite low.The microfractures in low permeability reservoir are similar to the inter-granular pores to some extent,so low permeability reservoir should be viewed as single-pore media,and can not be named dual-pore media.High compressibility and strong stress-sensitivity of low permeability reservoir are due to the systematical error in laboratory measurement,and are not the property of reservoir itself.The slippage effect and the threshold pressure gradient of reservoirs are false appearances of experiment and do not exist actually.

Key words: low permeability, microfracture, dual-pore media, compressibility, stress sensitivity, slippage effect, threshold pressure gradient