Mission Canyon Formation Reservoir Characteristics in North Dakota

Twenty-five oil fields productive from the Mission Canyon Formation, middle Madison Group were studied at four areas in the North Dakota portion of the Williston Basin. These areas are: 1. the Nesson Anticline (North Tioga, Tioga, Beaver Lodge, Capa, Hofflund, Charlson, Hawkeye, Blue Buttes, Antelope and Clear Creek fields); 2. northeast of the Nesson Anticline (Rival, North and South Black Slough and Foothills fields); 3. the eastern basin margin (Bluell, Sherwood, Mohall, Glenburn, Chola and Haas fields); and 4. the southern basin margin (Lone Butte, Little Knife, Big Stick, Fryburg and Medora fields). Mission Canyon reservoirs along the eastern basin margin, beneath the State “A” marker are housed in multiple shoaling-upward carbonate sequences composed of intraclastbearing, oolitic-pisolitic-oncolitic packstone/grainstones that underwent intense subaerial exposure. These barrier island/shoreline buildup complexes are backed by evaporites (shoreward) and grade into offshore marine deposits basinward. Repetitive shoreline progradations further basinward placed lagoonal, tidal flat and supratidal coastal sabkha evaporites over earlier deposited barrier island/shoreline buildup complexes. Along the southern margin of the basin, beneath the State “A” marker, only a single shoaling upward sequence is present, with reservoirs housed in dolomitized transitional openhestricted marine skeletal wackestones and restricted marine pelletal wackestone/packstones. Reservoirs along the Nesson Anticline were also deposited in a single overall shoaling upward sequence. Laterally equivalent evaporites are at a distance east and south of Nesson. Reservoirs at the Nesson Anticline’s northern end are housed in open marine skeletal packstone/grainstones and in buildup complexes of oolitic-pisolitic, intraclast-bearing, skeletal wackestone/packstones. At the Nesson’s southern end, reservoirs are interbedded limestones and dolostones. Limestones were deposited in a transitional open/restricted marine setting as slightly intraclastic, skeletal wackestone/packstones. Dolostones were deposited in a restricted marine setting as mudstones and skeletal mudstones and pelletal wackestones and packstones. Immediately above the State “A” marker the Rival (“Nesson”) Subinterval is productive northeast of Nesson Anticline. Reservoir rocks are composed of oolitic-pisolitic, intraclast-bearing packstones and grainstones deposited as barrier island/shoreline buildup complexes. The Rival also produces in the northern half of Nesson Anticline. Early deposition was dominated by barrier island/shoreline buildup complexes composed of oolitic-pisolitic packstones and grainstones to the north with evaporites southward.