South China Sea: Critical World Trade Route And Potential Source Of Hydrocarbons

Source: U.S. Energy Information Administration (EIA)

The South China Sea is a critical world trade route and a potential source of hydrocarbons, particularly natural gas, with competing claims of ownership over the sea and its resources.

Source: U.S. Energy Information Administration, International Hydrographic Organization
Representation of international boundaries is not necessarily authoritative

Stretching from Singapore and the Strait of Malacca in the southwest to the Strait of Taiwan in the northeast, the South China Sea is one the most important trade routes in the world. The sea is rich in resources and holds significant strategic and political importance.

The area includes several hundred small islands, rocks, and reefs, with the majority located in the Paracel and Spratly Island chains. Many of these islands are partially submerged land masses unsuitable for habitation and are little more than shipping hazards. For example, the total land area of the Spratly Islands encompasses less than 3 square miles. 

Several of the countries bordering the sea declare ownership of the islands to claim the surrounding sea and its resources. The Gulf of Thailand borders the South China Sea, and although technically not part of it, disputes surround ownership of that Gulf and its resources as well.

Asia’s robust economic growth boosts demand for energy in the region. The U.S. Energy Information Administration (EIA) projects total liquid fuels consumption in Asian countries outside the Organization for Economic Cooperation and Development (OECD) to rise at an annual growth rate of 2.6 percent, growing from around 20 percent of world consumption in 2008 to over 30 percent of world consumption by 2035. Similarly, non-OECD Asia natural gas consumption grows by 3.9 percent annually, from 10 percent of world gas consumption in 2008 to 19 percent by 2035. EIA expects China to account for 43 percent of that growth.

With Southeast Asian domestic oil production projected to stay flat or decline as consumption rises, the region’s countries will look to new sources of energy to meet domestic demand. China in particular promotes the use of natural gas as a preferred energy source and set an ambitious target of increasing the share of natural gas in its energy mix from 3 percent to 10 percent by 2020. The South China Sea offers the potential for significant natural gas discoveries, creating an incentive to secure larger parts of the area for domestic production.

Reserves and resources

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.

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.

Uncontested areas

The majority of current reserves exist in shallow water basins on the boundaries of the sea. This situation reflects limited exploration of deepwater areas. Vietnam, Malaysia, and Brunei have a long history of development in the South China Sea. Lacking significant onshore potential, they have invested in offshore technology, pipeline networks, and drilling; foreign partners often provide expertise. Consequently, these countries have the highest oil and gas reserves in the sea.

Over the past few years, however, companies have begun venturing farther offshore in an attempt to find new discoveries to compensate for declining fields. Relatively recent discoveries such as China’s Liwan 3-1 gas field, discovered in 2006, demonstrate the potential of deepwater exploration. Chinese national oil companies have built on initial successes in the Pearl River Mouth Basin and are rapidly expanding offshore activity in an effort to find new reserves and increase production.

Rather than attempting unilateral exploration and production (E&P) activities in disputed territory, several countries have opted to cooperate in the South China Sea. Malaysia and Brunei settled territorial disputes in 2009 and have partnered to explore offshore Brunei waters. Thailand and Vietnam have jointly developed areas of the Gulf of Thailand, despite ongoing territorial disputes. These success cases contrast with the parts of the South China Sea contested by multiple parties, which have seen little energy development.

South China Sea estimated proved and probable reserves

Country name	Crude oil and liquids reserves (billion barrels)	Natural gas reserves (trillion cubic feet)
Brunei	1.5	15
China	1.3	15
Indonesia	0.3	55
Malaysia	5.0	80
Philippines	0.2	4
Taiwan	-	-
Thailand	-	1
Vietnam	3.0	20
Total	11.2	190
Note: Reserve totals do not include Gulf of Thailand or onshore reserves. Reserve estimates are based on field ownership status. Sources: U.S. Energy Information Administration, Oil & Gas Journal, IHS, CNOOC, PFC Energy.

Contested territory

China claims to South China Sea

Spratly Islands

EIA estimates the region around the Spratly Islands to have virtually no proved or probable oil reserves. Industry sources suggest less than 100 billion cubic feet (Bcf) in currently economically viable natural gas reserves exist in surrounding fields. However, the Spratly Island territory may contain significant deposits of undiscovered hydrocarbons. USGS assessments estimate anywhere between 0.8 and 5.4 (mean 2.5) billion barrels of oil and between 7.6 and 55.1 (mean 25.5) Tcf of natural gas in undiscovered resources.

Evidence suggests that most of these resources are likely located in the contested Reed Bank at the northeast end of the Spratlys, which is claimed by China, Taiwan, and Vietnam. The Philippines began exploring the area in 1970 and discovered natural gas in 1976. U.S.-based Sterling Energy won the concession in 2002, and U.K.-based Forum Energy acquired the concession in 2005 and became its operator. However, Chinese objections halted further development, and the concession remains undeveloped.

Paracel Islands

The Paracel island territory does not have significant discovered conventional oil and gas fields and thus has no proved or probable reserves. Geologic evidence suggests the area does not have significant potential in terms of conventional hydrocarbons.

Exploration and production

The South China Sea poses extensive geological, technological, and political challenges to developing hydrocarbon resources.

While national oil companies (NOCs) have been successful in extracting hydrocarbons near the shorelines of the South China Sea, the majority of the area presents daunting challenges to development. In addition to the geopolitical disputes, the contested areas of the sea face geological and technological concerns [...]

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