Two exploration wells drilled by Repsol SA and Armstrong Energy LLC—Horseshoe 1 and the 1A sidetrack—have extended the Nanushuk play more than 20 miles south of the existing discoveries in the same interval in Alaska North Slope’s Pikka Unit (OGJ Online, June 5, 2015).
Repsol reported that the Horseshoe discovery qualifies as the largest US onshore conventional discovery in 30 years.
Drilled during the 2016-17 winter campaign, the Horseshoe 1 well reached 6,000 ft and encountered more than 150 ft of net oil pay in several reservoir zones in the Nanushuk section. The partners drilled the Horseshoe 1A sidetrack to a TD of 8,215 ft and encountered more than 100 ft of net oil pay also in the Nanushuk.
The companies estimate their blocks in the Nanushuk play could contain as much as 1.2 billion bbl of recoverable light oil. Repsol has not reported test results for the Horseshoe discovery, but previous wells—Qugruk 8 (Q-8) and Qugruk 301 (Q-301)—flowed 30° gravity crude at rates of as much as 2,160 bo/d and 4,600 bo/d, respectively.
Preliminary development concepts for Pikka anticipate start of production in 2021 with a potential rate approaching 120,000 bo/d.
Repsol holds a 25% working interest in the Horseshoe discovery and a 49% working interest in the Pikka Unit. Armstrong holds the remaining working interest and is currently the operator.