Hydrodynamic Effects on Mission Canyon (Mississippian) Oil Accumulations, Billings Nose Area, North Dakota

Mission Canyon oil production on the south flank of the Williston basin provides an example of an area in the mature stage of exploration that shows significant hydrodynamic effects on oil accumulations related to stratigraphic traps. The effects are illustrated by the Billings Nose fields and the Elkhorn Ranch field. The reservoirs have low hydraulic gradients of about 2 m/km (10 ft/mi), tilted oil-water contacts with gradients of 5 m/km (25 ft/mi), and variable formation-water salinities that range from brackish to highly saline. Oil accumulations in some zones are displaced off structure and downdip to the northeast, parallel to porosity pinch-outs. Other zones are pure hydrodynamic traps, lacking both structural and stratigraphic closure. Future success in exploration and development in the play will depend on recognizing the hydrodynamic effects and predicting oil displacement.