Tengizchevroil (TCO), a joint venture of Chevron Corp., ExxonMobil Corp., KazMunayGas, and LukArco, has let an engineering, procurement, and construction contract to Bechtel to build four crude-oil storage tanks at the TengizChevroil oil production facility in Tengiz, Kazakhstan. Bechtel also will modernize the fire and gas detection systems across the entire crude tank farm.