Dangerous mission down below

In one of his dives in the Bohai Sea, Chu stayed in the icy water for more than two hours.

"Have you ever seen a freezing man cry? That's what happened when I got out of the water," Chu says.

Data from the State Oceanic Administration shows more than half of the Bohai Sea was covered by ice on Jan 23, 2010, a historic record.

Exiting the water covered in ice floes was another challenge, because the floes can hurt divers in unpredictable ways.

"We have no choice but to dive under the water whenever there is a need," Chu says.

As the national offshore oil company, CNOOC has the responsibility to explore new energy resources for this fuel-hungry country with rapid economic growth. The increasing offshore drilling platforms have kept Chu and his team very busy.

Every year for the past nine years, he has spent up to 260 days at sea spending five Spring Festivals on board, including two underwater.

"Once at sea, the work is around the clock, and you need to be physically strong and mentally tough," Chu says.

Chu says he feels sorry for his wife and parents, who have to endure his long absences, and every time he sees his three-year-old son, the boy looks at him like he is a stranger, which breaks his heart.

The longest period he has spent with his wife is about one month, after his son was born.

"My son seldom talks to me," he says with a sigh.

Despite the dangers and long absences from home, Chu has never considered quitting his job.

"I can work till I'm in my 50s," he smiles.

Over the past nine years, Chu and his team have successfully completed 34 repair projects involving offshore oil and gas facilities, avoiding economic losses estimated at least 530 million yuan ($86 million), according to CNOOC.