Equinor has agreed to buy an additional 22.45% stake in the Caesar Tonga oil field from Shell Offshore for $965m in cash.

The purchase comes after Equinor exercised its preferential rights to increase its share in the deepwater US Gulf of Mexico asset.

With the latest acquisition, Equinor’s share in the field increases from 23.55% to 46.00%, while operator Anadarko will have 33.75% interest and Chevron 20.25%.

One of the largest deepwater resources in the US Gulf of Mexico, the Caesar Tonga field is situated around 290km south-southwest of New Orleans in the Green Canyon area. Equinor’s share of production from the field currently stands at 18,600 barrels of oil equivalent.

“Deepwater Gulf of Mexico forms an important part of Equinor’s portfolio.”

Equinor development and production international senior vice president for North America Offshore Christopher Golden said: “Deepwater Gulf of Mexico forms an important part of Equinor’s portfolio. This deal will strengthen our position in this prolific basin and build on the recent discovery in the Blacktip well.

“Later this year we will be drilling the Equinor-operated Monument prospect, which has the potential to further develop our position in the Gulf of Mexico.

“We are pleased to increase our presence in the US, one of our core areas. This is an asset we understand well, and our larger interest will deliver significant additional free cash flow from day one.”

In April 2019, Shell signed an agreement to sell the stake to Delek Group for the same consideration. This transaction was subject to “the right of first refusal held by the three other co-owners in the field”.

Equinor has been operating in the US Gulf of Mexico since 2005, owning stakes in eight producing fields and two under-development resources.

The completion of the acquisition is subject to customary closing conditions and approvals, with an effective date of 1 January 2019.