Abstract: On the basis of overall analysis in the deep sealing condition of the north of Songliao Basin,it was thought that the space time distribution of deep caprock is the disadvantage of the gas pool forming.The feature of discontinuous distribution determines that the gas can only accumulate and pools form in small areas.The disposing relation between K₁d₂caprock and the period of source rock discharge of K₁d₂ is better than that of K_1q1+2.Although the complicated faults can form a variety of traps,the long period and many-time-movement faults can also transport the gas into the mid shallow layer,which was the disadvantage of the conservotion of gas pools.