The Ministry of Land and Resources has established a goal of discovering 10 medium-sized oil fields and eight to 10 major natural gas fields on the mainland by 2010, as it steps up efforts to enhance national energy security. The oil fields should each have at least 100 million tonnes of reserves, while the gas fields will each have at least 0.1 trillion cubic metres (tcm) of reserves, according to the first national geological exploration blueprint issued by the ministry on Wednesday. The ministry did not specify whether the reserves refer to economically recoverable ones, or the broader geological reserves, which may include those too difficult or too costly to extract. 'It's not possible to make comparisons on these targets as it did not give definitions for the reserves,' said DBS Vickers analyst Gideon Lo Wai-yip. In its five-year plan, which spans 2006 to 2010, the ministry said it wanted to add 4.5 billion to 5 billion tonnes of proven geological oil reserves and 2.5 tcm to 2.8 tcm of gas reserves. This is up from 4.42 billion tonnes and 2.6 tcm achieved between 2001 and 2005. Some progress already has been made. The nation's largest oil and gas producer, PetroChina, had 11.61 billion tonnes of recoverable oil reserves and 1.51 tcm of gas reserves at the end of 2006, based on its filing with the Securities and Exchange Commission of the United States, where it is listed. Major finds in recent years include PetroChina's Nanpu oil field in the Bohai Bay rim, which contains 1.02 billion tonnes of geological reserves, of which 405.07 million tonnes are economically recoverable. Others are China Petroleum and Chemical's (Sinopec) Puguang gas field and PetroChina's Longgang gas field, both in Sichuan and estimated to hold more than 500 billion cubic metres of recoverable reserves. 'We have high hopes for major discoveries in the Xinjiang autonomous region, Daqing in the northeast, the South China Sea and the Beibu Bay area,' said Zeng Xingqiu, former chief geologist at Sinochem Corp. The ministry said it aimed to complete surveying a quarter of the nation's land mass on a 1:50,000 scale and half of its offshore area on a 1:1,000,000 scale by 2010. 'The US completed the 1:50,000 survey on the whole nation in the 1970s,' Mr Zeng said.