The deal, signed between Sultan of Brunei Hassanal Bolklah (right)
and Malaysian Prime Minister Najib Abdul Razak,
ends a disagreement between the two nations.
The agreement will see state-run producers Petronas and PetroleumBrunei, as well as US independent Murphy Oil jointly operate blocks CA1 and CA2 for the next 40 years, state-run news agency Bernama reported.
Murphy will take a 30% slice of CA2. Other details of the equity split, including that covering CA1, were not made public.
The two blocks are in the South China Sea, lying within the two nation's Commercial Arrangement Area along the Brunei-Sarawak maritime boundary off Limbang, the northernmost division of Sarawak.
The nations agreed in March last year that the disputed areas "are no longer part of Malaysia" but allowed Malaysia's state-owned Petronas to enter into new production-sharing contracts, AFP said.
Brunei had previously awarded exploration rights in one offshore block to French giant Total and another to Anglo-Dutch supermajor Shell.
But Petronas had awarded the same blocks to Murphy and its own subsidiary, Petronas Carigali.