Abstract:

Permian reservoirs in northwestern margin of Junggar Basin include sandstone,conglomerate,volcanic clastic rock and volcanic rock with low-medium porosity and permeability. The disperse distribution of porosity and permeability reveals the heterogeneity of the reservoir physical property. The pore spaces are mainly residual intergranular porosity, dissolution porosity in clastic rock reservoir,dissolution matrix porosity and fractures in volcanic reservoirs. Secondary dissolution porosity plays the key role of reservoir quality. The development of secondary porosity is closely related to depositional hiatus.Based on Q-mode fator analysis of eight variables of rock physical property and pore configuration, it is suggested that the lower limit of porosity is 9%; the lower limit of permeability of clastic rocks is 0.2×10^-3μm;the lower limit of the permeability of volcanic rocks is 0.2×10^-3 μm.The Permian reservoirs could be divided into four types accordingly.

Key words: Junggar Basin, secondary porosity, depositional hiatus, classification