Mubadala Development Co, the Abu Dhabi state-owned investor, will receive less revenue from its 51% stake in Dolphin Energy Ltd as the unit’s natural gas assets are returned to the Qatari government.

Earnings from the Dolphin gas project will “significantly decline” once the costs of building the project have been recovered, which is forecast to occur near the end of 2012, and the upstream resources are transferred to Qatar, Mubadala said in an update of its bond programme.

The investor’s two most significant profit-making joint ventures last year were Dolphin Energy and Emirates Aluminium Co, according to the document filed yesterday.

Dolphin was established in 2001 by Mubadala, Occidental Petroleum and Total and started to pipe gas from Qatar in 2007 to the UAE and Oman under a 25-year contract.

The upstream assets are jointly owned by the partners until they have recouped their costs, which is typical of production sharing agreements. The venture cost $ 6.2bn and the pipeline has a throughput capacity of 2.6bn cubic feet a day.

Mubadala’s hydrocarbon revenue has for the past three years mainly come from the sale of natural gas liquids and gas from Qatar’s offshore North Field and crude from the Jasmine field in Southeast Asia.

In 2011, 2010 and 2009, the income, net of royalties, accounted for 26.8%, 38.2% and 36.7% respectively of total revenue. Earnings from the sale of goods and services were 27.9bn dirhams ($ 7.6bn) last year, Dh15.8bn in 2010, and Dh13.1bn in 2009.

Under the terms of the development and production sharing agreement governing the upstream portion of the Dolphin project, the so-called dry gas produced by the plant is sold to Dolphin Energy.

Ethane produced by the plant, about 3,800 tonnes a day, is sold to Qatar Petroleum. The remaining output of about 3,750 tonnes a day of liquefied petroleum gases, more than 100,000 barrels a day of condensate and 700 tonnes a day of sulphur is sold to Qatar International Petroleum Marketing Co.