KHOBAR - Saudi Aramco Lubricating Oil Refining Co (Luberef) has invited Saudi-based companies to bid for the early engineering work to expand its Yanbu refinery, industry sources said. The tender documents for the front-end engineering and design (FEED) were released in December. Bids are due by March 15, sources said. Luberef was established in 1976 and produces around 550,000 tonnes per year (tpy) of oil lubricants at two refineries on the kingdom's Red Sea coast at Jeddah and Yanbu. The Yanbu refinery has a capacity of 280,000 tpy of oil lubricants. The expansion includes a new lube hydrocracker, raising the capacity of the vacuum distillation unit (VDU), upgrading the electrical facilities and adding new storage tanks, a source familiar with the bidding process said. He declined to say what the capacity of the refinery would be after the upgrade. Companies would receive the final description of the work on Feb. 22, sources said. US firm ExxonMobil sold Saudi Arabia's Jadwa Investment its 30 percent stake in Luberef in 2007. Aramco holds the remainder. Industry sources had said at the time Aramco wanted Luberef to expand, which did not fit in with Exxon's plans in the lubricant market. Japan's JGC Corp, Italy's Saipem, Foster Wheeler, US Jacobs Engineering are among companies bidding for the job.