State oil giant Saudi Aramco is expected partially start up its new Wasit gas plant in the first quarter of 2015 despite some difficulties linked to construction, three industry sources said.

Wasit will be one of the largest gas plants not linked to oil wells ever built by Saudi Aramco. It will process 2.6 billion cubic feet per day (bcfd) of non-associated gas from the offshore fields Hasbah and Arabiyah.

The plant, north of Jubail on the kingdom's Gulf coast, is expected to supply 1.75 bcfd of sales gas and could potentially produce up to 3.05 bcfd to meet peak summer demand.

In 2012, industry sources told Reuters Wasit was expected to be delayed by at least one year because the gas coming from fields offshore had higher sulfur content than expected. The plant was due to be completed this year.

"It will be partially in operation in the first quarter of next year, officially the project should be (fully) up and running mid-2015 but I think the more realistic schedule is sometime in 2016," one source familiar with the matter said.

Labour, logistics and subcontractor issues have also delayed a natural gas liquids (NGL) project at Shaybah, in the kingdom's southern Empty Quarter, a venture designed to help boost petrochemical feedstock, one source said.

"Train one will be in operation year end while the second train in March," the source said.

Saudi Aramco declined to comment on when both plants would be operational.

Shaybah NGL will process 2.4 bcfd of low-sulphur sweet gas from the Shaybah oilfield, and send on 275,000 barrels-per-day (bpd) of NGLs to a processing plant in Juaymah.

Aramco has said that Wasit and another project -- Karan-- that has already been in operation since 2012 will likely boost Saudi Arabian natural gas output by an estimated 40 per cent.  - Reuters