Chinese oil giant CNOOC on Friday reported that 2012 net profit fell 9.3 percent, blaming higher operating costs -- including exploration -- and the poor global economy.
The state-owned energy company said net profit for last year was 63.69 billion yuan ($10.25 billion), down from 70.26 billion yuan in 2011.
Revenue rose 2.8 percent to 247.63 billion yuan from 240.94 billion yuan the previous year.
The Beijing-based company attributed the fall in profits to the increased cost of searching for new wells and operating existing ones.
Operating expenses increased by 17.4 percent to 21.45 billion yuan, while exploration costs increased by 73.3 percent, the company said in a filing to the Hong Kong stock exchange, where it is listed.
CNOOC said it saw a net production 342.4 million barrels of oil equivalent, a 3.2 percent year-on-year increase, largely due to greater production from North American shale oil and gas projects and oil sands project in Canada.
In 2011 CNOOC took over Canadian oil sands developer OPTI for around $2.1 billion.
"During the year, faced by complex external conditions, the company overcame various unfavourable factors, seized opportunity to lay a solid foundation for development," CNOOC said.
Last month the oil company completed a $15.1 billion purchase of Canada's Nexen energy company, a move data analyst Dealogic described as China's largest foreign investment.
The company said Friday that the acquisition "laid down resources base for the company's long-term development and built a new overseas platform for the company".
China is the biggest energy consumer in the world, the second-biggest consumer of oil and has been snapping up resource assets across the globe in order to fuel growth.