* Shell offers assistance to Abu Dhabi company
* Leak shut in output on Tuesday
* Platform handles output from other North Sea fields
DUBAI/LONDON, Jan 16 (Reuters) - Abu Dhabi company TAQA said on Wednesday it has begun the process of restoring the flow of an estimated 80,000 barrels per day (bpd) of crude oil in Britain's Brent pipeline system, which forms part of the global Brent oil benchmark.
TAQA said on Tuesday it had found an oil leak in one of the legs of the Cormorant Alpha oil platform in the North Sea, closing the site and the Brent pipeline system that handles a total of 90,000 bpd, as a precaution.
As Brent is one of the four North Sea oils used as a benchmark to price oil around the world, partly via Brent crude futures, the system's closure supported global prices on Wednesday when several other factors were weighing on them.
"Investigations have found there is no connection between the Brent pipeline system and the pipeline involved in the release," TAQA said in a statement on Wednesday.
"The process of restarting Brent throughput follows a thorough technical evaluation that shows it is safe to do so without any increased risk to Cormorant Alpha."
Cormorant Alpha production, put at 10,000 bpd, remains closed while work on the platform leg continues, TAQA said.
The entire Brent system was expected to export around 135,000 bpd of oil this month, around 8 percent of British offshore oil production.
In an earlier update, TAQA said that none of the oil had been released into the environment and investigations continued to discover the source of the leak.
"Measurements within the leg show that the volume released is small," said the earlier statement.
The installation is owned and operated by the UK arm of the Abu Dhabi National Energy Co, TAQA Bratani Ltd.
Cormorant Alpha also handles oil from the Dunlin, Thistle, Northern producer, Murchison, North Alwyn, Tern, Eider and North Cormorant Platforms.
Shell U.K. said that the shutdown has not had any direct impact on its Brent Field installations, and offered to help TAQA with the repairs.
"An offer of technical and material support has been made to TAQA," a spokesperson said.
The Brent system is jointly owned by 21 companies. It consists of part of the processing systems and structure on the Cormorant Alpha platform, operated by TAQA, as well as a 150 km pipeline connecting Cormorant Alpha to the BP-operated Sullom Voe Oil Terminal in the Shetland Islands.
TAQA owns a 24 percent share of the terminal.
Benchmark Brent crude oil futures were down just 22 cents at $109.41 a barrel by 1843 GMT, although European data pushed down other risk-sensitive assets such as equities, and OPEC has released a downbeat assessment of demand for its oil output in 2013.