Saudi Aramco has invited engineering firms to bid for the construction of a power plant related to a natural gas liquids project at the kingdom's Shaybah oilfield, Reuters has reported, citing industry sources. Bids for the first package of work, a cogeneration plant, are due on November 22, according to the sources. The remaining three process packages, yet to be tendered, include a gas treatment facility, an NGL recovery plant and utilities, and facilities to handle gas.