The Three Forks formation
Geology, footprint, and mineral-owner context for the Three Forks, drawn from public USGS and state survey sources. Resource figures describe the play as a whole and are not a per-acre value. Every figure on this page is an estimate subject to verification of your specific interest.
Last updated June 2026.
What is the Three Forks?
The Three Forks is the dolomitic interval directly beneath the Bakken in the Williston Basin, and it is developed as a second stacked target across the same core North Dakota counties, McKenzie, Mountrail, Williams, and Dunn. The USGS assessed the Bakken and Three Forks together at a mean of about 4.3 billion barrels of undiscovered, technically recoverable oil, a play-wide figure rather than a per-acre yield.
The Three Forks sits immediately below the Bakken in the Williston Basin and was the discovery that effectively doubled the Bakken play. It is a dolomitic formation, often developed in multiple benches of its own, and because it lies just under the Bakken, operators frequently produce both from the same leases. That stacking is why a core North Dakota tract can support a substantial number of wells over the life of the field. The basin is mature, so value leans on existing production. For a mineral owner, a Three Forks interest behaves much like a Bakken interest, a seasoned, flatter-declining income stream valued on the standard income multiple applied to your real checks.
Three Forks geology
- Age and lithology
- Upper Devonian dolomitic siltstone and mudstone lying directly beneath the Bakken. Source: USGS Williston Basin assessment.
- Stacked benches
- Developed in multiple benches and produced together with the overlying Bakken from the same acreage.
- Where it produces
- The Williston Basin: the same core counties as the Bakken, McKenzie, Mountrail, Williams, and Dunn, with flank development elsewhere.
How much oil and gas the Three Forks holds
The USGS 2021 assessment of the Bakken and Three Forks formations of the Williston Basin estimated a combined mean of about 4.3 billion barrels of undiscovered, technically recoverable oil. This is an undiscovered play-wide estimate, not proven reserves and not a measure of any individual property.
Source: USGS Fact Sheet 2021-3058 (Bakken and Three Forks, Williston Basin, 2021 update).
Counties in the Three Forks play
These are the counties and parishes we cover where the Three Forks produces. Each links to local value context and the operators active there.
What the Three Forks means for your minerals
A resource estimate for a play is not the value of your acreage. Your mineral and royalty interest is valued on the income your wells actually pay, roughly 36 to 72 times your average monthly royalty check, the same as 3 to 6 times your annual royalty. Where you land in that band depends on your wells decline, the operator, your royalty rate, and any undeveloped drilling upside. For the full method and a free on-screen estimate, see what are my mineral rights worth.
The Three Forks is part of the Williston Basin. For the basin-wide value bands and the counties we buy in, see the Williston Basin page.
Three Forks questions
- What is the Three Forks formation?
- The Three Forks is an Upper Devonian dolomitic interval directly beneath the Bakken in the Williston Basin. It is a second stacked oil target developed alongside the Bakken across the core North Dakota counties of McKenzie, Mountrail, Williams, and Dunn.
- How is the Three Forks different from the Bakken?
- The Three Forks lies just below the Bakken and is a separate dolomitic reservoir. Operators commonly develop both from the same leases, which is part of why core Williston Basin acreage supports so many wells.
- How are Three Forks minerals valued?
- A Three Forks interest is valued the same way as any producing interest, on the income it pays, roughly 36 to 72 times your average monthly royalty check, with mature wells supporting a steadier valuation. USGS resource figures describe the whole play, not your property. This is an estimate, subject to verification, not an offer.
Sources
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