Abstract: On the basis of the shape of capillary pressure and relative per mea bility curve. and related parameters. the fracture characteristics of reservoir in Huoshaoshan oil-field were discussed. It is concluded that capillary pressure curve with low porosity, low permea ability, high displacement pressure, high mercury injection saturation and large platform segment resulted from open mini fracture after pressurization, while this kind of open fracture with high transmissibility mostly formed after the perforation of reservoir.Therefore, we presented a new idea: reservoir in Huoshaoshan oilfield exists as a critical body of rock mechanics, i. e. fracturing occurs once stress disturbance is imposed.

Key words: Junggar basin, Huoshaoshan oilfield, Capillary pressure, F ractured reservoir, Relative permeability curve