The Explorers 2021: Sidebar: Upending ANS exploration

Kay Cashman

Petroleum News

The Nanushuk formation forms part of the Brookian sequence, the youngest and shallowest of the major North Slope petroleum bearing rock sequences.

Although rocks of the Brookian are found across the entire North Slope, the Nanushuk is found mainly west of the central North Slope (see full story in the May 31, 2020, issue of Petroleum News, titled “Exciting outlook”).

Following the discoveries of the Prudhoe Bay and Kuparuk River fields in rock reservoirs much older and deeper than the Nanushuk, exploration mainly focused on these deeper rocks, with Brookian strata such as the Nanushuk generally ignored.

That is, until 2015, when Bill Armstrong took a contrarian view of conventional North Slope exploration strategies, brought in a well-heeled partner, Repsol, and made the Pikka discovery to the east of the Colville delta. That discovery upended expectations for potential oil volumes in the Brookian.

In late 2017 (closed in 2018) Armstrong and a minority partner sold their interest in the Pikka and Horseshoe area leases to Oil Search.

In its initial 2017 release of information Oil Search said it would “form a long-term partnership with Armstrong, leveraging its technical capabilities and experience in the identification of additional potential growth opportunities in Alaska.”

That deal with Oil Search gave Armstrong the opportunity to pursue his geologic ideas across the North Slope, as the companies signed an area of mutual interest agreement that allowed Oil Search to purchase 50% of any acreage Armstrong acquired in northern Alaska and take over operatorship of those leases.

Bill Armstrong, who had been following Oil Search since 2014, chose the ASX company over other bidders because he thought it was the best choice to move Alaska exploration and development forward.

- KAY CASHMAN