The Chinese state-owned oil company CNOOC has discovered a remarkable natural gas deposit in the South China Sea that could bring about decisive changes in the region’s energy policy.

CNOOC estimates that the new Lingshui 36-1 reservoir contains more than 100 billion cubic meters (3.5 trillion cubic feet) of natural gas in an ultra-shallow field in ultra-deep waters – the first field of its kind in the world. The gas layer lies just 200 meters below the seabed in 1,500 meters of water.

According to CNOOC, developing a commercial gas field at such a shallow depth beneath the seabed was considered impossible. However, this field should be able to produce a whopping 10 million cubic meters of natural gas per day.

CNOOC first announced the discovery in June, and it has now been confirmed by government regulators. Together with the previous discoveries, the total reserves in the region amount to over one trillion cubic meters. For comparison: This is about 1/60 the size of the Norwegian Troll field.

CNOOC has not disclosed the location of the field. China’s neighbors have not raised any protests against its development, suggesting it may be within China’s legitimate and internationally recognized EEZ off Hainan Island.

China also claims most of the South China Sea, including international waters and parts of its neighbors’ EEZs. It has previously clashed with Vietnam over energy E&P projects and has repeatedly shadowed and harassed drilling activities in Vietnamese-sponsored oil leases within Vietnam’s EEZ. In 2014 and again in 2016, China deployed its own rig to drill in disputed waters off Vietnam, leading to a diplomatic standoff.