New chairmen have been named for the country's top three State-owned oil companies as the sector faces a range of challenges including low global crude prices, industrial reform, a need for improved growth and the fallout from President Xi Jinping's anti-corruption campaign.

Wang Yupu, 59, deputy head of the Chinese Academy of Engineering, is replacing Fu Chengyu as chairman of Sinopec Group, Asia's largest refiner, the Organization Department of the Central Committee of the Communist Party of China announced on Monday.

However, the strategic path followed by the huge enterprise is likely to remain unchanged as the country deals with rising dependence on foreign supplies of crude, said Lin Boqiang, director of the China Center for Energy Economics Research at Xiamen University.

Li Li, research director at ICIS Energy, a Shanghai-based consultancy, said observers are eager to see whether Wang continues the openness and innovation that characterized the reform process under Fu.

Fu, 64, will retire after serving an extra year as chairman. Most heads of State-owned enterprises step down at 63, but Fu, who has led Sinopec since 2011, was allowed to remain beyond the designated age.

On April 27, China's anti-graft watchdog announced that Wang Tianpu, Sinopec's president, was under investigation for suspected "serious disciplinary violations", a euphemism for corruption.

Before that, Sinopec had largely escaped the attention of anti-graft investigators. In contrast, China National Petroleum Corp, the country's largest oil producer, had seen several senior officials face corruption probes.

The central government also announced that Wang Yilin, a former CNPC executive and current chairman of China National Offshore Oil Corp, the country's largest offshore energy producer, will become the chairman of CNPC.

Wang replaces Zhou Jiping, 63, who is retiring and has been CNPC chairman since 2013.

"CNPC is now facing multiple problems including sharply declining profits, the anti-graft campaign and the unclear direction of mixed-ownership reform," Li said. "Wang will have a lot on his plate."

Wang, born in 1956, became deputy general manager of CNPC after serving as head of the company's subsidiary in the Xinjiang Uygur autonomous region. He was appointed chairman of CNOOC during the last leadership reshuffle at the three oil giants four years ago.

His role at CNOOC will be taken by Yang Hua, the corporation's current president, the Organization Department said.

Yang, born in 1961, joined CNOOC in 1982, starting as an upstream oil exploration geologist. As chief financial officer, Yang played a crucial role during CNOOC's largest overseas takeover, the acquisition of Nexen Inc in 2013.