Overview: EIA estimates the South China Sea contains approximately 11 billion barrels of oil and 190 trillion cubic feet of natural gas in proved and probable reserves. Conventional hydrocarbons mostly reside in undisputed territory. Undiscovered resources could be greater. In November 2012, the Chinese National Offshore Oil Company (CNOOC) estimated the area holds around 125 billion barrels of oil and 500 trillion cubic feet of natural gas in undiscovered resources, although independent studies have not confirmed this figure.
It is difficult to determine the amount of oil and natural gas in the South China Sea because of under-exploration and territorial disputes. Most current discovered fields cluster in uncontested parts of the sea, close to the shorelines of the coastal countries. EIA estimates there to be approximately 11 billion barrels (bbl) of oil reserves and 190 trillion cubic feet (Tcf) of natural gas reserves in the South China Sea. These numbers represent both proved and probable reserves, making them closer to a high-end estimate. Energy consultancy Wood Mackenzie, for example, estimates the sea to contain only 2.5 billion barrels of oil equivalent in proved oil and gas reserves.
In addition to proved and probable reserves, the South China Sea may have additional hydrocarbons in underexplored areas. The U.S. Geological Survey (USGS) analyzed the potential for undiscovered conventional oil and gas fields within several geologic provinces of Southeast Asia in 2010 as part of its World Petroleum Resources Assessment Project. The study included a significant area of the South China Sea, which the USGS estimates may contain anywhere between 5 and 22 billion barrels of oil and between 70 and 290 trillion cubic feet of gas in as-yet undiscovered resources (not including the Gulf of Thailand and other areas adjacent to the South China Sea). These additional resources are not considered commercial reserves at this time because it is unclear how economically feasible it would be to extract them.
As the USGS assessment did not examine the entire area, undiscovered resources could be greater. In November 2012, the Chinese National Offshore Oil Company (CNOOC) estimated the area holds around 125 billion barrels of oil and 500 trillion cubic feet of natural gas in undiscovered resources, although independent studies have not confirmed this figure.
Read the full report: U.S. Energy Information Agency, South China Sea [Bien Dong] Reserves and Resources, Feb 7, 2013