UPDATE 2-UAE's ADNOC to boost gas output 1 bln cfd by 2013

* First stage to bring gas onshore to be completed this qtr

* Second stage set for start-up in 2013

* Sees first gas from Shah project by late 2013, early 2014

(Adds second official, background)

By Simon Web

ABU DHABI, Feb 1 (Reuters) - State-run Abu Dhabi National Oil Company (ADNOC) aims to boost gas output from its offshore fields by 1 billion cubic feet per day (cfd) by 2013, a senior official said on Monday.

The UAE holds the world's fifth-largest gas reserves, but has failed to keep up with rising domestic demand from power plants and industry. The Gulf Arab state depends on gas imports from Qatar to fire power stations and meet the needs of industry.

As part of measures to boost output, ADNOC plans to connect offshore gas production with its online grid, and the first stage of that would be completed in the first-quarter 2010, Ismail al-Ramahi, manager at the gas processing division of ADNOC, said during a speech at an industry event.

The second stage would start in 2013, he added. Together the two stages would bring 1 billion cfd onshore that would mostly supply the national grid, he added.

The state firm expected to see first production from the joint-venture with ConocoPhillips (COP.N) at the Shah sour gas field by late 2013 or early 2014, Ramahi said.

The gas at Shah has a content of around 30 percent of deadly sulphur dioxide, making it tougher to produce than conventional gas reserves.

The project, with an estimated cost of $10 billion, was expected to pump around 540 million cfd of gas to the national grid after processing 1 billion cfd of raw gas from Shah.

Aside from the offshore gas and the sour gas at Shah, ADNOC was also planning to substitute nitrogen and carbon dioxide for natural gas it currently injects in oilfields to maintain pressure and output of oil, he said. That would free up more gas for domestic supply, he added.

ADNOC's current gas output is around 6 billion cfd, he said.

The state oil company would also boost gas liquids output by 700,000 tonnes per year from July, Hasan al-Marzooqi, deputy general manager at ADNOC unit ADGAS, said at the same event. (Editing by Sue Thomas)