The three companies shortlisted are Saudi Basic Industries Company (Sabic), the US' Dow Chemicalsand Japan's Sumitomo Chemicals. Once a joint venture partner has been appointed, a tender will be issued for the front-end engineering and design (FEED) contract.

In addition to expanding the refinery, the joint venture will set up an ethane cracker with capacity of at least 1 million tonnes a year of ethylene, which will be used as feedstock for the production of polyolefin. Aramco plans to award a third-party concession for the cracker. The new complex will be located next to the existing refinery and will also include a propane dehydrogenation (PDH) unit at the refinery for the production of polypropylene. The UK office of Foster Wheelerhas recently completed a pre-feasibility study for the project.

Feedstock for the cracker will be pumped from the Eastern Province via the east-west pipeline. Aramco plans to convert one of the two coast-to-coast crude pipelines, the smaller 48-inch-diameter line, to carry gas to the Western Province. The conversion is estimated to cost about $800 million. A new pipeline spur will then link the east-west line with the Rabigh spur.