Time of migration may be determined by an analysis of: (1) compaction, which is a function of depth of burial and governs the time of primary migration or expulsion of hydrocarbons out of the source beds; (2) time of regional tilt, which initiates lateral or secondary migration; (3) time of formation of traps; (4) hydrostatic pressure which governs the gas capacity of traps and determines the earliest time of final accumulation; (5) saturation or bubble-point pressure, which is a function of depth of burial at time of migration and fixes the time of final accumulation; (6) history of lithologic development, that is, time of cementation and mineralization, time of development of secondary porosity, et cetera.

Each of these factors indicates the approximate time of migration and accumulation. An interpretation of the composite picture gives the "time of migration."

Application of these relationships in Alberta, Canada, indicates that accumulation of oil and gas in the Upper Devonian reservoirs of Nisku (D2) and Leduc (D3) age occurred during Colorado (Upper Cretaceous) time. As a result of this study, it has been possible to suggest the source of some Alberta crude oils.