China Petrochemical, the nation's second-largest oil and gas producer and the most aggressive state-backed acquirer of overseas assets, has agreed to pay US$4.8 billion for 30 per cent of the Brazil unit of Portugal's largest energy firm, Galp Energia. The deal will increase the exposure of China Petrochemical - parent of listed China Petroleum & Chemical (Sinopec) - to the vast offshore oil and gas potential in Brazil, which is poised to become one of the world's top holders of oil reserves in the next few years thanks to major discoveries in deep-water regions. China Petrochemical said it expected the deal to add daily oil and gas output of 21,000 barrels of oil equivalent in 2015, with peak output forecast in 2024 of 112,500 barrels-equivalent per day. China Petrochemical average daily output last year amounted to 1.39 million barrels-equivalent. Sinopec has the vast majority of the group's domestic oil and gas production assets but only a tiny portion of its overseas projects. In March, president Wang Tianpu unveiled Sinopec's 2015 oil and gas output target which translated into average annual growth of just 1.2 per cent to 2.8 per cent from last year. But the target did not include potential overseas assets it may buy from the state-owned parent, which had said it will inject them when their returns are acceptable to Sinopec's shareholders. They were pursued by the parent in the first place because they are either too risky or too big for Sinopec to swallow. Galp's assets in Brazil span stakes in 21 projects in seven basins, including the Santos basin where it has invested in the Lula field. Lula is the biggest oil find in the Americas since the giant Cantarell field in Mexico was discovered in 1976. Its share of proved, probable and possible reserves in the 21 projects amounted to 554 million barrels-equivalent at the end of last year, Galp said. Based on China Petrochemical's 30 per cent stake purchase, it could be entitled to 166 million barrels-equivalent of the reserves. The US$4.8 billion acquisition price works out at US$28.9 a barrel. Mirae Asset Securities head of energy research Gordon Kwan said Asian oil firms were increasingly looking at unconventional resources to feed their energy demand. 'It is another confirmation of the end of the easy oil era,' he said. 'Cash-rich Asian oil companies must struggle with more difficult oilfields in deeper waters and unconventional oil sands. Opportunistic acquisitions overseas is one important element of their [effort to enhance] national energy security.' China Petrochemical has spent around US$32 billion since 2005 on overseas oil and gas exploration and production assets, compared to US$12 billion of rival China National Petroleum Corp and US$10 billion of CNOOC, according to International Energy Agency data. Chinese firms have spent US$15.6 billion this year on overseas oil and gas assets, according to Dealogic. They spent US$24.4 billion last year.