BEIJING - China's top refiner, Sinopec Corp, has discovered a shale gas well located at a depth of 4,417 meters with maximum daily output of 105,000 cubic meters in Southwest China, authorities said Wednesday.

According to the Ministry of Land and Resources, the gas well is the deepest so far in the country and its exploration marks a technological breakthrough in China's deep shale gas drilling.

The project, named Dingye-2HF, is situated in Xishui county of Guizhou province, said the ministry. It is expected to be another important shale gas exploration block in Southwest China. Another shale gas block in the region, located in Fuling district of Southwest China's Chongqing municipality, produced 150,000 cubic meters per day last year.

The Dingye-2HF gas well is expected to have an average daily output of 43,000 cubic meters and output will be stable, according to the ministry.

Shale gas is natural gas that is found trapped within shale formations. As a clean and efficient energy source, it has become an increasingly important source of energy throughout the world.

China is seeking shale gas development to ensure energy security and optimize energy structure. According to a shale gas plan for 2011-2015, China aims to produce 6.5 billion cubic meters of shale gas annually by 2015.