The 7,000-metre borehole was drilled into the Tibetan Plateau, called the roof of the world, in a bid to tap the region's oil and natural gas resources, the Hong Kong-based South China Morning Post reported quoting Chinese engineers. "It is the deepest borehole ever drilled at such extreme altitudes, according to mainland scientists who are following the project," the report said.
The world's deepest borehole, the Kola Superdeep Borehole in Russia, was drilled to a depth of 12,262 metres by the former Soviet Union in 1980s.
Tibet's remoteness, thin air and lack of infrastructure have so far saved it from the unchecked exploration and extraction of fossil fuels and minerals but the Himalayan region can escape the hunt for oil and gas as the government wants to lessen the dependence on their imports, it said. But the latest project is shrouded in secrecy.
Professor Li Haibing, a researcher with the Chinese Academy of Geological Sciences, would not reveal the project's location and declined to identify which state-owned oil companies were active in the region, the report said. Li said Chinese government was reviewing a proposal for a new "deep-earth" exploration project "submitted by the nation's most prominent geologists" to drill wells more than 10 kilometres deep to obtain study samples, with Tibet being an area of the greatest interest. "Tibet's altitude and geology make it among the world's most difficult drilling locations. Fragmented [geological] structures, prone to collapse, increase the risks," said Li.
Li, who led one of the largest scientific drilling projects in Tibet, and works for the academy's Institute of Geology, also noted that "oxygen scarcity at higher elevations drains workers' energy considerably".
China's handling of exploration of minerals as well as plans to efforts to build dozens of dams on the Brahmaputra and other rivers in Tibet has come under criticism from ecologists considering the fragile nature of the region.
Eighty-three workers were killed when a massive landslide with about two million cubic meters of mud engulfed Jiama Copper Gold Polymetallic Mine near Lhasa last year which was attributed to excessive mining.
China has been keeping a low profile about its exploration of resources in Tibet due to the sensitivity of the region, which has seen growing political and religious strife. The discovery of commercially viable flows of oil and natural gas has the potential to develop Tibet's economy.
Wei Wenbo, a geologist with the China University of Geosciences and an expert on Tibetan geology, said scientists continue to debate Tibet's oil and gas potential. It is hoped that samples from the seven-km borehole will clarify some of the questions about the region's hydrocarbon and mineral resources.
Wei said, "It is one of the last virgin territories for natural resource exploration on the planet, drawing interest from miners and drillers at home and abroad". However, he warned against a rush to exploit Tibet's rich mineral veins. "Exploration and extraction of minerals and hydrocarbons in Tibet will require massive capital expenditure," he said, noting that infrastructural construction and drilling at such high altitudes drives up labour and logistics costs.
Wei said mining projects had the potential to irreversibly damage Tibet's fragile ecosystems. "Environmental impact studies must be undertaken and risks assessed before commercial projects are approved," he said. The two largest state-owned oil and gas companies, China National Petroleum Corporation (CNPC) and China Petroleum and Chemical Corporation (Sinopec), did not respond to queries about their projects in Tibet, the Post report said.
But information on their websites indicate that both firms have had footprints in the region for nearly 20 years.
CNPC began exploring the Qiangtang Basin in central Tibet in 1995 and subsequently estimated the basin's oil reserves at 10 billion tonnes, or more than 70 billion barrels.
In 1997, Sinopec established its first exploration centre in Nagqu county, with the aim of mapping the surrounding area with detailed seismic surveys and experimental drilling.
Last August, the China Geological Survey, under the Ministry of Land and Resources, signed a 20 million yuan (USD 3.5 million) exploration agreement with Sinopec after the Tibet region showed "enormous oil and natural gas potential," according to the ministry's website.