Houston-based super independent ConocoPhillips said Tuesday it has an agreement with BP plc that would, among other things, boost its holdings in a legacy development in Alaska.

In simultaneous transactions, ConocoPhillips agreed to acquire BP’s 39.2% interest in the Greater Kuparuk Area in Alaska, as well as its 38% interest in the Kuparuk Transportation Co. for an undisclosed price.

ConocoPhillips already had an estimated 55% stake in the Greater Kuparuk Area, where it has worked with co-owners BP, Chevron Corp. and ExxonMobil Corp., which are the state’s leading producers.

ConocoPhillips has worked in the Greater Kuparuk Area of the North Slope for years. It operates the Kuparuk River Unit, North America’s second largest oilfield, 40 miles west of Prudhoe Bay. Production at Kuparuk began in 1981 and reached a milestone in July 2005 when cumulative production reached 2 billion bbl. The area has produced more than 2.5 billion bbl to date.

ConocoPhillips and its co-owners have invested more than $5.6 billion to develop the field and optimize oil recovery. Kuparuk Drill Site 2S (DS2S), the first new drill site in more than 12 years, celebrated first oil in October 2015. DS2S is expected to add about 8,000 b/d gross at peak production.

BP’s full-year 2017 production in the Greater Kupark Area was 38,000 boe/d, with year-end proved reserves estimated at 190 million boe.

The acquisition is subject to co-owner pre-emption rights; both acquisitions are subject to regulatory approval.

In turn, ConocoPhillips has agreed to sell BP a 16.5% stake in the Clair field offshore Scotland while retaining a 7.5% interest. No financial details were disclosed. Chevron and Royal Dutch Shell plc also have minority stakes in Clair.

The transactions “are inter-conditional and expected to close simultaneously following regulatory approvals,” ConocoPhillips said. Excluding customary adjustments, the transaction prices are expected to be cash neutral to both companies.

“These transactions are significant for ConocoPhillips because they continue our strategy of coring up our legacy asset base in Alaska, while retaining an interest in the Clair field in the UK,” said CEO Ryan Lance. “We have a long history of creating value in Alaska and an ongoing commitment to invest in our legacy assets, as well as in the development of our recent exploration success.

“Likewise, we are committed to maximizing the value of our assets in the UK North Sea, including continued investment in our operated assets in the Central North Sea.”

ConocoPhillips’ stakes in Clair resulted in full-year 2017 production of 3,000 boe/d, with year-end proved reserves estimated at 40 million boe.