Less is known about migration than any other process involved in the accumulation of hydrocarbons in the subsurface. It is generally described as that unknown process or group of processes that enable petroleum to move from a source to a reservoir. | Less is known about migration than any other process involved in the accumulation of hydrocarbons in the subsurface. It is generally described as that unknown process or group of processes that enable petroleum to move from a source to a reservoir. |