Cut Bank Field lies in Glacier County, Montana, about fifty miles east of Glacier National Park and extending to within three miles of the Canadian border. It is a large field by area — roughly thirty-one miles long and up to ten miles wide — sitting on the west flank of the Sweetgrass Arch in a monoclinal setting. Oil and gas activity in the area dates to the 1920s, the first commercial well came in around 1931, and by 1936 Cut Bank had become Montana’s top-ranking oil field.
Exploration around Cut Bank began in the 1920s, when the Sweetgrass Arch was recognized as a regional high that could trap hydrocarbons migrating out of the deeper basin to the west. Gas was found before oil, and the roster year of 1926 refers to that early phase rather than to commercial crude. The first commercial oil well is generally placed around 1931, and by 1933 the field was producing strongly enough to change the economy of northern Montana, drawing workers into a county that had been almost entirely agricultural.
The 1930s were Cut Bank’s decade. The field became Montana’s leading oil producer in 1936, and its shallow Kootenai sandstone — known simply as the Cut Bank sand — proved extensive enough to support drilling across an area larger than most Rocky Mountain fields occupy. Because the trap is monoclinal rather than a tight anticline, the productive area spreads over many townships, which is why Cut Bank generated an unusually large number of separate leases and, in time, an unusually large number of royalty owners.
The field settled long ago into stripper production supported by injection, and wells across Glacier County continue to operate at low rates decades after the boom ended. Owners in this area should be aware of the jurisdictional geography: the Blackfeet Indian Reservation lies immediately west, and mineral interests within reservation boundaries are trust or allotted acreage administered by the Bureau of Indian Affairs rather than fee minerals conveyed under Montana law. The two kinds of ownership sit close together on the map and are governed entirely differently.
Cut Bank produces principally from the Cut Bank sand, the basal sandstone of the Lower Cretaceous Kootenai Formation, on the west flank of the Sweetgrass Arch. The trap is monoclinal rather than a simple closed fold, so the accumulation spreads across a broad area — about thirty-one miles long and up to ten miles wide — instead of concentrating on a crest. Deeper Madison carbonate production has also been established in the region. Shallow depths kept drilling and workover costs low, which is the main reason marginal wells here have remained economic for so many decades.
Cut Bank has been produced with water injection to maintain pressure in the Kootenai sand, the standard treatment for a broad, shallow sandstone reservoir with limited natural drive. Enhanced recovery in a field of this shape is as much a matter of arithmetic as engineering: with production spread thinly across a very large area, the economics depend on keeping per-well operating costs low rather than on dramatic flood responses. The result is the classic northern Montana stripper profile — small volumes per well, very long lives, and decline rates measured over decades.
Cut Bank minerals are widely distributed and heavily fractionalized, a direct consequence of a productive area spanning many townships and ninety years of inheritance. Individual royalties are small; the underlying mineral acres are frequently worth more than the income suggests. The essential first step in this county is confirming whether a tract is fee land or lies within the Blackfeet Reservation, where trust and allotted interests are BIA-administered and are not fee minerals we can buy. Where the interest is fee, we buy minerals and royalties in Glacier County and provide free written offers.
County-level well data, production charts, and selling guides for the counties this field spans:
Activity in the area dates to the 1920s and the first commercial well is generally placed around 1931. The field was producing strongly by 1933 and became Montana’s top-ranking oil field in 1936. Earlier dates in field rosters usually refer to gas discoveries.
Because the trap is monoclinal on the west flank of the Sweetgrass Arch rather than a compact anticline. Oil is held in the Cut Bank sand across roughly thirty-one miles by up to ten miles, which is why so many separate tracts and leases are involved.
Interests inside reservation boundaries are generally tribal trust or individually allotted acreage administered by the Bureau of Indian Affairs, not fee minerals conveyed under Montana law. They cannot be sold the way fee minerals can, and we do not purchase them.