China National Petroleum Corp (CNPC), the country's top oil producer, said Tuesday its listed arm aims to increase its capacity on joint venture projects to 15 million tonnes a year by 2015.

The target for PetroChina Co is more than double the 6.57 million tonnes of oil equivalent its 23 joint oil and gas projects with foreign companies produced last year, CNPC said in a statement.

Such joint projects represent a fraction of the total 165.2 million tonnes of oil equivalent PetroChina produced last year, according to the company's annual report.

Shanghai-listed PetroChina had signed contracts with 48 foreign oil companies in 12 countries as of the end of 2008.

One of those projects, the Changbei gas field in northern Shaanxi province, a joint venture between PetroChina and Royal Dutch Shell PLC, reached its production capacity of three billion cubic metres late last year, two years ahead of schedule.

The Dagang Zhaodong oil project between PetroChina and Australia's Roc Oil Co in the shallow waters of Bohai Bay in northern China has maintained annual crude oil output above one million tonnes for six years.

PetroChina is also working with Chevron Corp to develop the high-sulfur Chuandongbei block in southwest Sichuan province.