South Korean SK Engineering and Construction Co, Daelim Industrial Co, and GS Engineering and Construction have submitted the most competitive bids for the construction of three big units for the Yanbu refinery which Saudi Aramco is building with ConocoPhillips, Reuters has reported, citing industry sources. Aramco and Conoco were pleased with the outcome of bids and are unlikely to hold a second round of negotiations with companies competing for the engineering, procurement and construction packages of the refinery, sources told the news service.