St. Croix Plugs Wildcat Northeast of Wolf Point

Roosevelt County, Montana

Denver-based St. Croix Operating (St. Croix) has plugged and abandoned their initial vertical exploration on the Montana side of the Williston Basin. The operator has put cement to the Buck Elk #1, nw-nw 36-32n-48e, which spots inside the Fort Peck Indian Reservation. Projected to evaluate the Devonian, this exploratory test bottomed in the Nisku at a depth of 7,750’. Although most data are still being held confidential, according to partial information released to the state, tops encountered in the Buck Elk #1 include the Dakota at 3,960’, Mission Canyon at 6,280’, Bakken at 7,472,’ and the Nisku came in at 7,615’, beneath a ground elevation of 2,404’.

St. Croix’s dry hole sits less than a quarter-mile east of a wildcat proposed in 2009 by Dickinson, N.D.–based Armstrong Operating (Armstrong). At the time, Armstrong was considering drilling a vertical Duperow attempt in the ne-ne 35-32n-48e. The Dickinson firm never permitted this well, however, which would have had a total depth approaching 8,000’.

The nearest deep exploration to St. Croix’s failed Buck Elk #1 is roughly 2 miles to the northwest at a dry hole drilled in 1966 by Superior Oil. The Larry Rosebud #1, se-ne 28-32n-48e, bottomed in the Souris River at a depth of 8,297’. Prior to abandonment, two drillstem tests were conducted in the wellbore, one in the Nisku and a second in the Duperow.

The Nisku interval from 7,686’ to 7,732’ produced 3,961’ of muddy salt water, while the Duperow zone at 8,126’–8,149 delivered 155’ of muddy water and 3,220’ of brackish water. A core taken in the Nisku between 7,675’ and 7,732’ contained a 3’ section described as “a Dolomite that had good porosity and fluorescence, along with good staining and strong odor.” Tops picked in this wellbore included the Mission Canyon at 6,377’, Bakken at 7,550’, Nisku at 7,685’, Duperow at 7,764’, and the Souris River came in at 8,260’, beneath a KB elevation of 2,583’.

Another conventional wildcat near St. Croix’s Buck Elk #1 spots some 2 miles to the northeast. Drilled by Texaco Inc., the Fort Peck Tribal B #1, nw-nw 17-32n-49e, achieved a total depth in the Winnipeg of 9,274’. Six drillstem tests were conducted in this attempt, two in the Charles and one each in the Lodgepole, Nisku, Duperow, and Interlake. The only hydrocarbon shows came from the Lodgepole interval at 6,744’–6,781’, where 1,164’ of slightly gas-cut muddy salt water was recovered. This dry hole was plugged in 1966.

The nearest established production to St. Croix’s setback is roughly 6 miles to the southeast at a developmental test in Long Creek Field, a single-well Madison oil pool discovered in 1975 by the Pennzoil Company. The Longee #1, ne-ne 32-31n-49e, accessed the Ordovician Red River at a depth of 9,485’ and was given an IPP of 28 bopd and 52 bwpd from vertical Charles perforations at 6,430’–6,472’. Prior to completing this well in the Madison, Pennzoil conducted several drillstem tests below the Mississippian section. A DST run across the Nisku at 7,784’–7,810’ recovered 4,499’ of salt water with ­sulfur odor. The sampler held 2,360 cc of salt water, with no shows of oil or gas. Pennzoil also performed a straddle-packer test in the Duperow from 8,210’ to 8,240’ that reversed out 188’ of water cushion and 7,992’ of salt water. The chamber contained 3,000 cc of salt water.

To date, the Longee #1 has cumulated more than 58.9 k bo and 96.1 k bw. Tops picked in this wellbore include the Charles at 5,917’, Nisku at 7,763’, Winnipeg at 9,479’, and the Red River at 9,638’. Following numerous operatorship changes, the Longee #1 is now under the control of Wichita, Kan., independent Darrah Oil.

Previous activity conducted by St. Croix in the Williston Basin took place in August 2017, when the firm drilled a dry hole in Bottineau County, North Dakota. Representing a stepout to North Haas Field, a Madison reservoir, the Northern Border #1, se-sw 7-163n-82w, bottomed at a total depth of 3,956’. This Madison failure spots some 3.5 miles south of the Canadian border.