State-run Abu Dhabi National Oil Company (Adnoc) is to choose between two competing proposals for transporting sulphur from the Shah gas field, near the border with Saudi Arabia.

The rival plans are a 264-kilometre-long pipeline and a rail link. Both schemes would link the Shah field to gas-processing and distribution facilities at Habshan, and export facilities at Ruwais.

The US’ Fluor Corporation is working on a front-end engineering and design (Feed) contract for the pipeline, while US engineering firm Wilbur Smith is preparing proposals for the rail link on behalf of state-run Union Railway Company.

The amount of sulphur produced at the field will increase once work on the $10bn development of the Shah field finishes in 2014.

On 12 October, Union Railway announced that Adnoc had asked it to build a railway line to carry sulphur between the three sites. The announcement led engineering executives contacted by MEED to assume that Adnoc had cancelled the proposed pipeline.

However, one senior executive close to the pipeline project tells MEED that Adnoc and its joint venture partner on the scheme, the US’ ConocoPhillips, will choose between the proposals once the engineering studies have been completed. “Fluor will continue with its designs, as will Union Railway,” says the executive. “Both plans should be completed by the end of the year, when Adnoc will be able to make a decision.”

Abu Dhabi-based oil and gas contractors say the pipeline proposals are complex because the sulphur needs to be kept at 120-155°C. The pipeline must also prevent the sulphur from mixing with water as the two create highly corrosive sulphuric acid on contact.

Union Railway says the new line would carry 7 million tonnes a year of granulated sulphur from Shah to the Ruwais export facility.

One source close to the scheme tells MEED that Union Railway will complete a Feed study for the line by the end of 2009.

If it goes ahead, the sulphur railway will be an extension to the AED30bn ($8.1bn), 1,400km Union Railway network, which will transport passengers and cargo across the UAE. Once completed in five to seven years time, the railway will be able to transport 3 million containers a year and 30 million tonnes of bulk.