Briscoe Abandons Northern Powder River Basin Wildcat

Crook County, Wyoming

Representing the firm’s first exploratory activity in their home state, independent operator Briscoe Petroleum (Briscoe) of Sheridan, Wyo., has failed to find production at a vertical wildcat in the northeastern portion of the Powder River Basin. Drilled by CapStar Rockies rig No. 312, Briscoe recently cemented the State #4-36, nw-nw 36-56n-68w, a 4,500’ Minnelusa probe.

Located in Crook County, some 36 miles northeast of Gillette, Wyo., and 5 miles west of the Campbell county line, this straight-hole failure bottomed in the Pennsylvanian at a depth of 4,325’. Log tops encountered in the attempt include the Muddy at 2,290’, Dakota at 2,576’, Chugwater at 3,405’, Opeche at 4,065’, and the Minnelusa came in at 4,158’ beneath a ground elevation of 3,952’. The estimated cost to drill this prospect was roughly $400,000.

Briscoe’s dry hole sits less than a quarter-mile north of a duster drilled in the 1960s by Houston-based R.E. Hebbert. The Brunel 67-9294 #1, sw-nw 36-56n-68w, bottomed in the Minnelusa at a depth of 4,186’ and was plugged in 1965 with no cores taken or tests conducted. Tops picked in this failure include the Dakota at 2,536’, Morrison at 2,848’, Goose Egg at 3,819’, and the Minnelusa came in at 4,076’, beneath a KB of 3,965’.

A similar distance northwest of the State #4-36 letdown, Mobil Oil attempted to establish Pennsylvanian reserves at the 26G W-043050 #F44, se-se 26-56n-68w. This effort bottomed in the Minnelusa at a depth of 4,490’. Two DSTs were conducted in the wellbore, the first in the Minnekahta and a second in the Minnelusa. The Minnekahta drillstem test across the interval at 4,150’–4,188’ recovered 957’ of sulfurous mud-cut water with flecks of black oil. The second DST was performed in the Minnelusa from 4,245’ to 4,259’, where the pipe reversed-out 2,643’ of slightly brackish water. With no production casing run, Mobil plugged the 26G W-043050 #F44 in 1963.

Approximately a half-mile northeast of the State #4-36, British American Oil drilled a straight-hole well at the Broyles W-063001B #1, se-sw 25-56n-68w. After reaching a total depth in the Pennsylvanian of 4,172’, one drillstem test was conducted in the Minnelusa between 4,128’ and 4,141’. The only recovery noted was 3,740’ of sulfur water, and the failure was abandoned in 1963.

In addition to Mobil, SWEPI (Shell Oil) also looked for Minnelusa reserves in this area. Some 2 miles south of Briscoe’s setback, Shell drilled an attempt at the Federal W-054553 #43-2, ne-se 2-55n-68w. With no cores cut or tests performed, this 6,051’ exploratory effort was cemented in 1962.

The nearest Minnelusa production to Briscoe’s State #4-36 is roughly 5 miles to the southeast at two vertical producing wells in Corral Creek Field, a Minnelusa oil pool. Discovered in 1962, this stratigraphic-type trap has cumulated more than 749.9 k bo and 19 mmbw from the vertical Minnelusa at depths near 6,100’.

As previously mentioned, the State #4-36 dry hole was Briscoe’s first wildcat attempt in the Wyoming section of the Powder River Basin. Prior to drilling this Minnelusa failure, the Sheridan-based operator had been active along the northwestern flank of Montana’s portion of the Powder River Basin, where they attempted to find shallow Pennsylvanian Amsden reserves.

The most recent exploration by Briscoe in the Treasure State took place in August 2018, when the company completed the Kendrick Heirs #13-32, sw-sw 32-1n-35e, Big Horn County. The Wyoming independent has released no data or results from this foray, which was slated to evaluate the Pennsylvanian Amsden at a depth of 6,014’. Briscoe’s shallow effort scales approximately a mile north of the Crow Indian Reservation.

Roughly 2.5 miles southwest of the Kendrick Heirs #13-32, Briscoe re-established Tensleep production in Montana’s Snyder Field, an abandoned oil pool. Since March 2017, the Kendrick Heirs #4-6, nw-nw 6-1s-35e, has cumulated more than 5.3 k bo and 33.7 k bw from the vertical Tensleep at depths approaching 4,600’. Latest daily gauge shows that during October 2018, this well averaged 15.4 bopd and 127 bwpd.

Discovered in 1952, Snyder Field is a Tensleep oil pool that produced sporadically prior to its abandonment in 2001. Cumulating more than 477.6 k bo, this reservoir remained inactive until Briscoe’s completion of the Kendrick Heirs #4-6.

Briscoe has drilled several other shallow Amsden prospects in this general area of Montana, without success.