Chinese energy giant CNOOC Group is studying the possibility of building a multibillion-dollar floating liquefied natural gas (FLNG) vessel, as-yet untried technology that would likely be used to produce gas from the deep waters of the South China Sea. While the state-run company has made no public announcement, a pre-feasibility study was well under way, CNOOC and other industry officials said. CNOOC was already talking to global engineering firms about possible joint design of the vessel, two industry officials added.