Both the compositional maturity and structural maturity of Ⅱ

4-6

and Ⅳ

1-4

reservoir rocks in the north Part of Shuanghe oilfield are relatively low

and the types of authigenic and clay minerats are various

pete-structural diameters and the size of pore-throats varies distinctly

microscopic anisotropy.is high and micro-potes developed wed. The considerable variation of reservoir POre structures in lateral diredion and Plenty of microdistributive pattern of oil and water lead to low oil-expulsion. The reservoirs mentioned above are predominatly type-Ⅱ and type-Ⅲ ones.