China is eyeing more overseas opportunities for its offshore drilling and completion technologies at high-temperature and high-pressure gas fields, according to the nation's largest producer of offshore oil and gas, China National Offshore Oil Corp.

China's technological capacity to independently develop high-temperature and high-pressure gas fields is only second to that of the United States, said Li Zhong, chief engineer of CNOOC's Zhanjiang branch.

The know-how and innovation being deployed in the South China Sea, which was granted first prize in this year's National Science and Technology Awards, has been successfully applied to the HTHP gas fields at home and abroad, including eight HTHP gas fields in the Gulf of Mexico, seven in Europe's North Sea and 18 in Iraq, said Li Yanjun, chief executive engineer of HTHP drilling and completion of CNOOC's Zhanjiang branch.

According to the Ministry of Land and Resources, nearly 15 trillion metric tons of natural gas lies there, one-third of the total in the South China Sea.

However, temperatures at the seabed stratum can reach 249 C, while the pressure there is equivalent to putting 125,000 tons on a surface of one square meter, both of which present unique challenges to oil and service companies.

"Drilling and completing a well at deep water is no easy task," said Li Yanjun.

"One of the harshest environments in the industry, the South China Sea's volatile conditions include battering from the wind, cold temperatures, constant moisture from storms and mist from the high winds."

This environment makes the South China Sea one of the most demanding of all offshore oil and gas exploration territories, along with the North Sea and the Gulf of Mexico.

Six international petroleum companies came to China back in the 1980s in an attempt to overcome technical difficulties, only to end up yielding very little after a huge spending.

Backed by the National High-tech R&D Program and in the framework of a National Science and Technology Major Project, CNOOC has been conducting its own exploration since the 1990s. After two decades of research, CNOOC Zhanjiang Branch has cut the average drilling period from 175 days to 52 days, and reduced costs by 70 percent.

The technology, which enables gas exploration to penetrate the hard seabed to reach gas beneath scalding rock formations, has generated direct revenue of 21.6 billion yuan ($3.4 billion) and indirect revenue of 356.5 billion yuan in the past seven years since its application, while substantially improving efficiency and security, said Li Yanjun.

"We are confident the technology will be applied to more HTHP gas fields home and abroad to help boost efficiency and further tap the potential of deep sea energy."