Cedar Hills Field straddles the North Dakota and Montana line in the southwestern corner of the Williston Basin, across Bowman and Slope counties in North Dakota and Fallon County in Montana. Continental Resources opened it in 1995 by drilling horizontally into the Red River B — a dolomite roughly ten feet thick that vertical wells had never made pay. The field became Continental’s largest asset for years and is one of the clearest examples anywhere of a reservoir that only works because of the way it is drilled and produced.
The Ordovician Red River had been drilled vertically across southwestern North Dakota for decades with frustrating results. The B interval is thin — on the order of ten feet of finely crystalline dolomite — and a vertical wellbore simply cannot contact enough of it to justify the cost. Continental Resources began leasing the Cedar Hills area in 1993 on the theory that a horizontal wellbore running thousands of feet inside that thin zone would change the economics completely.
The theory held. Continental drilled the discovery in 1995, and the field that followed was later described as among the largest onshore oil fields in the lower 48 states ranked by proved liquid reserves. Just as important, the company paired horizontal drilling with high-pressure air injection — an unusual secondary recovery method in which compressed air is injected into the reservoir, where a slow in-situ oxidation reaction maintains pressure and helps drive oil toward producing wells.
Cedar Hills accounted for a large share of Continental Resources’ reserves and production for years before the company’s Bakken and Oklahoma positions eclipsed it, and Continental has long been the name associated with the field. The combination of horizontal drilling and air injection at Cedar Hills is frequently cited as a template for producing thin carbonate reservoirs, and versions of the approach were applied elsewhere along the Red River trend in both states.
The Red River B is an Upper Ordovician dolomite lying deep in the southwestern Williston Basin, with productive net pay commonly around ten feet. It is finely crystalline, with modest porosity and enough permeability to flow — unlike the Bakken, this is a genuine conventional reservoir. The problem was never the rock quality but the thickness: a vertical well contacts a few feet of pay, while a horizontal well can stay inside the interval for thousands of feet and drain a far larger volume of rock.
High-pressure air injection is the distinguishing feature of Cedar Hills. Compressed air is injected into the reservoir, where oxygen reacts slowly with the residual oil in place. That reaction consumes the oxygen, generates heat and flue gas, and maintains reservoir pressure, sweeping oil toward the horizontal producers. It is a genuine secondary recovery process, and it means Cedar Hills behaves like the long-lived conventional floods of the Permian rather than like a Bakken shale field a hundred miles north.
A Cedar Hills royalty is a very different asset from a Bakken royalty. Air injection supports reservoir pressure, so production declines slowly and the stream is long-lived and comparatively predictable — closer to a waterflood than to a shale well. That stability is valuable, but it also means the interest is priced on decades of remaining life rather than on near-term flush production, and buyers vary widely in how they model it. We buy minerals and royalties in Bowman, Slope, and Fallon counties and provide free written offers.
County-level well data, production charts, and selling guides for the counties this field spans:
Compressed air is injected into the reservoir, where oxygen reacts with residual oil in a slow in-situ oxidation. The reaction consumes the oxygen, produces heat and flue gas, and keeps reservoir pressure up, pushing oil toward producing wells. It is used at Cedar Hills as a secondary recovery method alongside horizontal drilling.
No. It produces from the Ordovician Red River B, a conventional dolomite far deeper and much older than the Bakken, in the southwestern corner of the basin. Its production behavior — slow decline supported by injection — is the opposite of a Bakken horizontal well.
Each state regulates the wells and spacing within its own borders, and your interest is determined by your acreage inside each unit. Records may be filed in courthouses in both states. We run title on both sides as part of preparing an offer, at no cost to you.