China has successfully excavated combustible ice--a kind of natural gas hydrate--from below the floor of the South China Sea after nine years of research in this field, a senior official said here Tuesday.
The development could ease China's energy dependence on oil and coal.
Zhang Hongtao, deputy director of the China Geological Survey Bureau, told a press conference held by the Ministry of Land and Resources that on the morning of May 1, China succeeded in collecting samples of combustible ice from the northern part of the South China Sea, making China the fourth country in the world after the United States, Japan and India to succeed in this field.
He said the success also proves that the northern part of the South China Sea is rich in natural gas hydrate resources.
A preliminary survey shows that the volume of natural gas hydrate in the continental slope of the researched sea area could reach 10 billion tons of oil equivalent.
Zhang said this makes the Shenhu sea area the world's 24th district from which samples of natural gas hydrate have been extracted.
He said the first sample was drilled 183-201 meters under the seabed, with a hydrate rate of 20 percent. The hydrate-containing sedimentary strata is 18 meters thick, and the hydrate contains 99.7 percent of methane.
The second sample was excavated 191-225 meters under the seabed, with the hydrate rate ranging from 20 percent to 43 percent. The hydrate-containing strata is 34 meters thick and the hydrate contains 99.8 percent of methane.
Natural gas hydrate usually exists in seabed or tundra areas. It is formed by natural gas and water in conditions of high pressure and low temperature. It looks like ice and can be lit up like solid ethanol, hence the name "combustible ice". Approximately 164 cubic meters of natural gas can be released from one cubic meter of natural gas hydrate.
It has been estimated that the total volume of organic carbon in the world's natural gas hydrate is twice the combined volume of the world's proven coal, oil and natural gas reserves.
International scientific circles have predicted that natural gas hydrate is the best replacement for oil and natural gas. Some developed countries have set the year 2015 as a deadline for tackling this new energy.