DUBAI, Feb. 18 (Xinhua) -- The Abu Dhabi National Oil Company (Adnoc) signed an agreement with Spanish oil and gas company Cepsa, awarding it a 20 percent stake in Abu Dhabi's offshore SARB and Umm Lulu concession, the state news agency WAM reported on Sunday.

The choice of Cepsa "underpins ADNOC's strategy to maximise returns from its resources, expand its downstream business, and retain value for the UAE," according to WAM.

The agreement was signed by Dr. Sultan bin Ahmad Sultan Al Jaber, Minister of State and ADNOC Group CEO, and Pedro Miro, Vice Chairman and CEO of Cepsa.

Abu Dhabi, the capital of the UAE, harbours approximately seven percent of the world's known oil reserves.

The concession area is made up of two main fields under development, Umm Lulu (Arabic for "mother of the pearl") and SARB, as well as two smaller fields, Bin Nasher and Al-Bateel.

Cepsa contributed a participation fee of 5.5 billion dirham, (1.5 billion U.S. dollars), to enter the concession, which also takes into account previous Adnoc investments in the concession area.

Adnoc, wholly owned by the Abu Dhabi government, retains a majority 60 percent stake in the concession that will be operated by its subsidiary Adnoc Offshore, The agreement has a term of 40 years and and will come into effect on March 9 2018.