International dredging firms have submitted technical proposals for a deal to expand export facilities at the Port of Ruwais in Abu Dhabi, as part of the $10bn Shah gas development.

As many as seven contractors have entered the first round of bidding on the estimated $500m deal, outlining their plans to expand the port to make space for new sulphur export facilities.

Bids went in to Abu Dhabi Gas Industries Company (Gasco) at the end of January, according to sources close to the deal.

A date has not been set for the submission of commercial bids.

The bidders include Belgium’s Dredging International and Jan de Nul; Royal Boskalis Westminster and Van Oord, both of the Netherlands; China Harbour Engineering Company (Chec); Geneva-based Archirodon Construction; and the local National Marine Dredging Company.

The scheme is part of a wider $10bn development to produce 1 billion cubic feet of sour, or sulphur rich, gas from the southern Shah field.

The joint venture partners on the scheme, Abu Dhabi National Oil Company (Adnoc) and the US’ ConocoPhillips, want to build facilities capable of handling 9,200 tonnes a day of solid sulphur at Ruwais.

Fears have grown in recent months over the feasibility of the project and the relationship between the partners.

Commercial bidding on all the main construction and management packages of the development have been delayed until March while Adnoc and Conoco decide the best way to transport the sulphur to processing facilities at Habshan and the Ruwais terminal (MEED 2:2:10).

The partners are set to choose between a railway scheme or a technically complex liquid sulphur pipeline.

However, sulphur export facilities will have to be built regardless of progress on the main scheme, according to executives close to the scheme, because the emirate will have to handle increasing volumes of sulphur in the coming years.

In 2008, Adnoc said sulphur production would top 7 million tonnes a year by 2013.

In September 2009, Gasco put a tender for a separate sulphur export terminal at Ruwais on hold as it moved to integrate the Shah gas facilities with other schemes in the emirate.