The Xihu Trough is a region in the East China Sea, located approximately 400 kilometres east of the cities of Shanghai and Ningbo. The Xihu Trough falls within the territorial waters of China. The region is a repository for natural gas, and consists of the Chunxiao, Tianwaitian, Canxue, Duanqiao, and Pinghue fields. The entire trough is approximately 500 kilometres long, and runs parallel to the Chinese coast.
On August 19, 2003 it was announced that Sinopec, CNOOC, Royal Dutch/Shell and Unocal had entered into a joint venture to exploit the gas reserves in the trough, beginning in mid-2005. Gas production is expected to reach 2.5 billion cubic metres a year by 2007.
