Royal Dutch Shell expects production of oil products at its multi-billion dollar joint venture gas-to-liquids project in Qatar to start in a "matter of weeks," a senior executive said on Tuesday.

This would mark the start of commercial production at the world's largest GTL facility, and Shell's second plant, which is expected to cost $18-19 billion.

"It's very exciting because it's a huge start-up," vice president for strategy Dick Benschop told reporters at an industry event in the Malaysian capital. "The first crude is there and the product will be there soon."

Plant operator Shell said in March it had started output from natural gas wells offshore, allowing the first sour gas to flow through a subsea pipeline into the giant GTL plant onshore.

"Every production is commercial, but there will be a ramp-up," Benschop said.

The 140,000 barrels per day Pearl GTL plant should come on line by the end of the year and reach full capacity in the first quarter of 2012, Tasweeq's CEO told Reuters on Sunday.

Pearl, a joint development by Qatar Petroleum and Shell, will process about 3 billion barrels-of-oil-equivalent over its lifetime from the huge North Field stretching from the Qatari coast into the Gulf.

The plant will produce oil products such as diesel, kerosene, lubricant oils, naphtha and paraffin. - Reuters