UPDATE 2-Sumitomo Chem to study Saudi Rabigh expansion

* Saudi Aramco, Sumitomo to complete study by Q3 of 2010

* PetroRabigh II aims to start operating by Q3 of 2014

(Adds details)

TOKYO, April 20 (Reuters) - Sumitomo Chemical Co (4005.T) and state oil company Saudi Aramco aim to expand operations at their Petro Rabigh 2380.SE joint venture petrochemical complex by the third quarter of 2014, the Japanese company said on Monday.

The two firms said they will conduct a feasibility study on further development and will aim to complete the study of the Saudi plant by the third quarter of 2010.

Turmoil in world credit markets and tumbling oil prices have prompted energy firms globally to review more expensive projects or cut back on spending to preserve liquidity.

They will consider increasing the capacity of the existing ethane cracker to take in an additional 30 million cubic feet per day of feedstock ethane.

The venture will also consider building a new aromatics complex using around 3 million tonnes per year of naphtha as feedstock, and will also look at constructing various petrochemical units, the two companies said.

A Sumitomo Chemical official said at a briefing on Monday he thought the estimated cost for the project would be in the range of several hundred billion yen, but declined to give a specific figure.

Last month, Japan's Nikkei business daily reported that PetroRabigh could spend up to 500 billion yen ($5.05 billion) to build the new petrochemical complex. [ID:nT68446]

Sources told Reuters earlier this month that Aramco has delayed plans to expand capacity at its Ras Tanura refinery, as well as build a giant petrochemical joint venture with Dow Chemical Co (DOW.N). [ID:nSP269307]

Aramco has laid out plans for 144 projects until 2014, including eight "giant" projects, it said last month, without giving a timetable. ($1=98.94 Yen) (Reporting by Mariko Katsumura and James Topham)