Saudi Aramco’s Korean subsidiary S-Oil has said it is considering investing more than $4.5bn on a petrochemical project in the Asian country, which would be ready by 2023.

"S-Oil is conducting a feasibility study into building a mixed feed cracker with the size of 1,500,000 tonnes per annum and olefin downstream facilities... to expand its petrochemical business portfolio", S-Oil said in a statement.

The new facilities will be built in the southeastern city of Ulsan, where S-Oil’s 669,000 barrels a day (b/d) refinery is located.

Aramco is the largest shareholder in the company, holding 63.4 per cent of the stake, with the remaining shares traded on the Korean stock market.

S-Oil is South Korea's third-biggest refiner by capacity.

While Gulf energy giants already have key downstream projects operating at home, and further projects in the pipeline, the natural next step in an expansion strategy is to invest abroad.

Leading the regional pack in downstream foreign investments is Saudi Aramco, which has refining and petrochemical joint ventures (JV) planned or subsidiaries operating in South Korea, Indonesia, Malaysia, China, India and the US.