The Red River Formation oil in the Williston Basin may have started to migrate as early as the end of the Santonian (84 Ma), before the Laramide Orogeny. The study area extends from Latitude 46N to 51N and from Longitude 100W to 107W, which covers more than 348,000 square kilometers of the Williston Basin in Saskatchewan, Manitoba, Montana and North Dakota. To identify Santonian migration routes in the Red River Formation, paleostructure, paleohydraulic head and paleowater salinity were determined in order to create an oil migration model for the Red River at that time. Modelling the original migration routes and understanding the current controls on oil accumulations provides new exploration fairways for the Red River Formation across the Williston Basin.