Abstract：First，on the basis of researching on mechanism and forming period of pressure seal for undercompacted shale cap，and by the relation of interval transit time to porosity and porosity to anomalous pore-fluid pressure，true method of which determines the forming period of pressure seal for undercompacted shale cap has been constructed by using interval transit time .Then based on that，by comparison with massive hydrocarbon drained period of source rock，the meaning of forming period of pressure seal being in researching on the effectiveness of that undercompacted shale cap pressure sealed hydrocarbon has been explained. Finally，using shale cap of Qingshankou Formation in Sanzhao depression of Songliao basin for an example，the research on forming period of pressure seal and effectiveness of sealing Jurassic and gas itself has been conducted using above-mentioned method. The result shows that the technique is feasible.
付广, 薛永超, 杨勉 . 用声波时差资料确定欠压实泥岩盖层压力封闭形成时期及其意义[J]. 石油地球物理勘探, 2000, 35(5): 634-640.
Fu Guang，Xue Yongchao, Yang Mian. Determine forming period of pressure seal for undercompacted shale cap and its meaning by using interval transit time data. OGP, 2000, 35(5): 634-640.
