There are three modes of secondary oil migration

including stable displacement mode

fingering mode

and spring mode.In order to observe the changing patterns of oil saturation

residual oil saturation

and the ratio of residual oil volume to pathway space under these three migration modes

glass cylinder systems with mediums of different materials and different grain sizes packed with wet-packing method were used to carry out experiments with buoyancy as the only driving force or pumping pressure and buoyancy as the combined driving force. The results show that the oil saturation of the migration pathway and the ratio of residual oil volume to inner space of cylinder vary greatly under different migration modes

while the residual oil saturation remains almost the same.