GEO ExPro

Exploration Update - Alaska

Largest US onshore oil discovery in 30 years
This article appeared in Vol. 14, No. 2 - 2017

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Armstrong Energy and partner Repsol have made the largest US onshore conventional hydrocarbons discovery in 30 years, with the drilling of the Horseshoe 1 NFW and the subsequent Horseshoe-1A sidetrack, drilled on ADL 392048 in the North Slope region of Alaska. Both well bores were drilled during the 2016–2017 winter drilling campaign and the results verify the Nanushuk as an important emerging play. 

Horseshoe-1 was drilled to a TD of 1,828m and encountered over 45m of net oil pay in several reservoir zones in the Nanushuk section. Horseshoe-1A sidetrack was then kicked off and drilled to a total depth of 2,504m, encountering more than 30m of net oil pay in the Nanushuk in the process. 

The contingent resources identified in Repsol and Armstrong Energy’s blocks in the Nanushuk play in Alaska could amount to ~1.2 Bb of recoverable light oil. The Horseshoe discovery extends the play more than 32 km south of the existing 2014 and 2015 discoveries achieved by Repsol and Armstrong in the same interval within the Pikka Unit. Preliminary development concepts for Pikka anticipate first production in 2021, with a potential rate of close to 120,000 barrels of oil per day. 

Repsol holds 25% WI in the Horseshoe discovery and 49% WI in the Pikka Unit. Armstrong holds operatorship and the remaining working interest. 

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