By adopting the method proposed by Edword D.Pittman in reprocessing the mercury injection curves obtained from reservoirs in the third member of Shahejie Formation in Huimin sag

the apex versus pore apertures are determined and their relationship with porosities and permeabilities is established.An analysis of the relationship between the apex versus pore aperture and the hydrocarbon enrichment indicates that reservoirs in the third member of Shahejie Formation in Huiming sag are lithologic traps or structural-lithologic traps with normal pressure

and the minimum apex versus pore aperture depends on the height of the oil column in traps provided that effective oil source presents.In the deep Linnan subsag

the third member of Shahejie Formation is obviously over-pressured and its minimum apex versus pore aperture is determined by the trap height and the formation pressure.The relationship between the apex versus pore apertures of sandstone and its hydrocarbon enrichment reflects the hydrocarbon accumulation dynamics in different basins.With the presence of source rocks and traps

the existence of hydrocarbon accumulation in different reservoiring conditions depends heavily on the apex versus pore apertures.