Discovery has 10pc of mainland's reserves PetroChina, the nation's biggest oil producer, has made a discovery in an offshore field in Bohai Bay with proven reserves equal to about 10 per cent of the country's oil and gas reserves. The find of 405.07 million tonnes of oil equivalent, believed to be one of the biggest oil discoveries in China for more than 30 years, might help ease the nation's strong demand for imported crude in the coming years and extend its economically exploitable crude oil reserves life by a year, analysts said. 'The Bohai Bay is a relatively mature area and this new discovery is encouraging,' Mark McCafferty, the lead analyst for Southeast Asia at energy consultant Wood Mackenzie, told Reuters. 'I'm sure it is a big find but exactly how big is uncertain as they tend to have a different methodology for reporting reserves in China.' The oilfield, at the Nanpu block of PetroChina's Jidong oilfield, has oil and natural gas reserves of more than one billion tonnes or 7.3 billion barrels of oil equivalent (boe), of which about 405.07 million tonnes, or 2.96 billion boe, are of proven reserves, according to a statement on the website of PetroChina's state-owned parent China National Petroleum Corp yesterday. Jidong oilfield, at Tangshan in Hebei province, covers 1,570 square kilometres, including 1,000 sqkm offshore and 570 sqkm onshore. 'The discovery is important to the nation's oil industry and development, as well as helping the economic development of the Beijing-Datang-Tianjin region,' the company said. The proven reserves were equal to about 15 per cent of PetroChina's oil and gas proven reserves as of the end of 2005 and about 10 per cent of the nation's oil and gas reserves as of the end of last year, analysts said. PetroChina had proven reserves of 19.55 billion boe at the end of 2005, according to its annual report. 'The company believes the Jidong Nanpu oilfield is a bulk, quality and efficient oilfield,' PetroChina said last night. It 'has characteristics such as good physical property of the oil-bearing layer, quality oil product, [and] well-performed testing production.' China's remaining economically exploitable oil reserves stood at 2.04 billion tonnes, or about 14.9 billion barrels, at the end of last year, while those of natural gas were 2.45 trillion cubic metres, or 14.4 billion boe, according to government figures. The country in March revised downwards the life of its economically exploitable crude oil reserves to 11 years from 14 to 15 years after it changed its calculation method to align with international practices. PetroChina president Jiang Jiemin said on March 19 it had made the country's biggest oil find in a decade in Bohai Bay, without giving details. The new oilfield was the largest the country had discovered over the past 10 years, with estimated output equivalent to 5.4 per cent of total national crude production last year, Xinhua reported, citing sources from PetroChina, on March 28. The report said PetroChina would release details about the field soon.