Between July 26 and Aug. 23, the North Dakota Industrial Commission issued orders authorizing Slawson Exploration to drill multiple dual-lateral wells on existing spacing units in the Squaw Antelope-Sanish pools in McKenzie County and in the Van Hook-Bakken pool in Mountrail County.
Slawson submitted applications for the dual-lateral wells in May. Hearings on the applications were held on May 30.
Most of the oil production from the Williston Basin’s Bakken petroleum system comes from the prolific middle Bakken, non-shale reservoir. Slawson was the first company to economically produce from actual upper Bakken shale, the source of the crude in the middle Bakken and Three Forks reservoirs.
Slawson will drill five dual-lateral wells into the upper Bakken shale on existing 1,280-acre spacing units and five dual-laterals on existing 640-acre spacing units in the Squaw Gap-Bakken pool in southwest McKenzie County.
The first lateral of each well in Slawson’s dual well drilling procedure is drilled conventionally into the upper shale. A liner with external isolation packers is installed and hung in the production casing and a whipstock is then installed above the first lateral within the Lodgepole formation just above the upper shale and a window is cut in the casing through which the second upper shale lateral is drilled and lined.
The second lateral is fractured by running a stimulation tie-back string into the second lateral liner, which is then allowed to produce for approximately 30 days. The tie-back string is pulled, the well is killed and the whipstock pulled, and then the first lateral is fracked. The first lateral is allowed to produce for approximately 30 days after which its fracture stimulation tie-back string is pulled and both laterals are allowed to produce and comingle.
Van Hook and Antelope field wells
Across the county in the Antelope-Sanish pool Slawson will drill three dual-lateral wells in an existing 320-acre standup spacing unit. Three of the dual-laterals will target the middle Bakken formation while the other two target the first and second benches of the Three Forks formation.
However, unlike the Squaw Gap wells, the Antelope dual-lateral wells will be stacked, dual-target wells with the upper lateral targeting the middle Bakken and the lower lateral targeting the second Three Forks bench.
Slawson will drill these dual-laterals using the same methods as the Squaw Gap wells. In the Antelope wells, the Three Forks lateral will be drilled and fracked first, followed by the second lateral that will be drilled into the middle Bakken. As with the Squaw Gap wells, the second lateral will be fracked and allowed to produce for approximately 30 days, then the first lateral will be fracked.
In the Van Hook field in southeast Mountrail County, Slawson got the go ahead to re-enter and cut a window in an existing single lateral middle Bakken well and drill a second lateral which will also target the first bench of the Three Forks formation. Drilling and completion procedures are the same as with the other dual-lateral wells.
Well economics
Slawson’s well economics for the Squaw Gap dual-lateral wells indicate estimated ultimate recoveries, EURs, of 400,000 barrels of oil. For the dual-laterals in the Antelope-Sanish pool, Slawson put the EUR at 650,000 barrels and an EUR of 225,000 barrels for the Van Hook Three Forks re-entry well.
Slawson said dual-lateral wells are less expensive to drill. For example, Slawson said a single lateral on a 640-acre unit costs approximately $5 million, or approximately $10 million for two laterals, while a dual lateral on a 640-acre unit comes in at approximately $7.5 million for a savings of approximately $2.5 million. Dual-laterals on 1,280-acre units result in similar if not greater savings according to Slawson.
Other Slawson dual-lateral applications
Orders have yet been issued on other dual-lateral well applications that Slawson filed in May. In those applications, Slawson is seeking authority to drill additional re-entry dual-lateral wells in the Elm Tree field in McKenzie County and in the Big Bend and Ross fields in Mountrail County.
In the Ross field, the second lateral will target the middle Bakken. In the Elm Tree field the second lateral will target the second bench of the Three Forks formation, while in the Big Bend field the second lateral will target first bench. Slawson reports an EUR for the first bench in the Big Bend field of 225,000 barrels, and 400,000 barrels for the middle Bakken in the Ross field as well as the second bench in the Elm Tree field.
