That said, the cost of filling China’s S.P.R. and the lack of transparency with regard to its S.P.R. program management are cause for concern.

China initiated the S.P.R. concept in 1993 but it didn’t launch the project until 2003, when it began building tank farms. The above-ground facilities have a total capacity of 100 million barrels, enough for 16 days of consumption. The first facility started operation in 2006 in Zhenhai, with the other three expected to come online by the end of this year. The latest reports suggest that the Zhenhai facility, with 33 MM-bbl of oil storage, has been fully filled.

Thus, over the past two years or so, China has been buying extra crude for the sole purpose of storing it. And that new demand for energy comes on top of China’s voracious appetite for crude oil and refined products. Furthermore, the program has only begun its first phase, the tank farms. Additional demand will reverberate through the market as the country begins buying oil to fill the storage facilities planned for the second and third phases.

In these, the government will build underground facilities or use existing salt caverns to stockpile crude. The second phase calls for building a storage facility in the northwestern city of Chongqing, with a capacity of some 50 MMbbl. Other candidates include the provinces of Gansu, Guangdong, Hubei, and Hainan.

The National Oil Reserves Center was established to build and manage the S.P.R. According to China’s new energy law, domestic oil companies like CNPC must build up their own reserves to supplement the S.P.R. In 1999, China set quotas for CNPC and Sinopec that require them to stockpile refined products for emergency use. Following the recent earthquake in Sichuan Province, the government released 61,000 barrels of diesel from CNPC’s Gansu Province stock, which was then transported to the market in Sichuan.

In addition to the supply and cost issues, China must decide whether it wants to be tied to the International Energy Agency (I.E.A.), which coordinates the global S.P.R. network. Its management of a collective S.P.R. response system offers more security than can any single country’s reserves.

China is ambivalent towards the I.E.A. It may be willing to join the group of oil-consuming nations, but it doesn’t like the idea of submitting its S.P.R. management to the I.E.A. However, China is worried that supply crunches may trigger social and political instability. The existing I.E.A. energy security system could offer protection for China’s interests in the event of instability. And the agency recently invited China to participate in its emergency response exercise.

China has established a relationship with the I.E.A., but it lacks a voice at the table where the world’s major energy importers regularly discuss new developments in energy markets and S.P.R. coordination, as well as energy policy and energy technology matters. China’s participation in the I.E.A.’s collective emergency response system could improve that system, which in turn would benefit China’s energy security and perhaps even help stabilize world oil prices.

The 27-member agency was created in 1974 to coordinate S.P.R. management by major oil-importing countries. It has twice organized S.P.R. releases in response to sudden supply disruptions: during the Gulf War in 1990 and after Hurricanes Rita and Katrina in 2005. The I.E.A. has advised China on the creation of its S.P.R. and it has urged it to be more open, saying that uncertainties worry the market and increased transparency would help reduce speculation.

That said, many of the countries that maintain S.P.R.s aim to have a 90-day supply of oil in storage. If China were aim for that target, it would need to stockpile about 700 million barrels. And as the country seeks to hit that mark, it would buy even more crude on the open market, thereby driving prices higher still.