Norwegian oil services company Odfjell Drilling said Tuesday it amended its contract with BP to work off the coast of Angola through 2015.

The company amended its contract with BP's subsidiary in Angola to deploy its Deepsea Stavanger rig in the deep waters of Block 18 of the Angolan coast.

The Norwegian company said the contract, worth an estimated $120 million, adds to an existing deal and includes the drilling of six wells. The contract secures the rig for BP's operations in Angola through 2015.

There was no statement from BP on the contract for Odfjell Drilling. In its profile for Angola, the company said Block 18 and the surrounding region entered into production in 2007 and produces on average 180,000 barrels of oil per day.

BP's net average production from Angola is around 200,000 bpd.

Angola is a member of the Organization of Petroleum Exporting Countries. OPEC said Angola has proven crude oil reserves of 9 billion barrels and 9.7 trillion cubic feet of natural gas.