Photo taken on June 21, 2017 shows the trial mining site in the Shenhu area of the South China Sea. [Xinhua/Huang Guobao]

BEIJING -- China has extracted about 235,000 cubic meters of the combustible ice from the South China Sea, beating previous expectations for the mining operation.

Wednesday afternoon marked six weeks of an ongoing mining operation in waters near the Pearl River estuary, without being disrupted by this year's second typhoon Merbok, according to operators of the trial mining site in the Shenhu area of the South China Sea.

"China has beaten expectations in completing the trial explorations of combustible ice using local innovations in technology and engineering. It marks a historic breakthrough," according to a statement released by the mining site.

Combustible ice usually exists in seabed or tundra areas which have the strong pressure and low temperature necessary for its stability. It can be ignited like solid ethanol, which is why it is called combustible or flammable ice.

One cubic meter of combustible ice, a kind of natural gas hydrate, is equal to 164 cubic meters of regular natural gas.

China declared its first success in collecting samples of combustible ice in the South China Sea on May 18 after discovering the substance in the South China Sea in 2007.

Photo taken on June 21, 2017 shows a drill machine on the trial mining site in the Shenhu area of the South China Sea. [Xinhua/Huang Guobao]