CNOOC technologies lauded for gas exploration

On the open water of the South China Sea, a drill sinks through the mounting pressure of the cold sea water, finally penetrating the hard seabed to reach the gas hidden beneath the scalding rock formations.

Areas that hide 4,000 meters below the sea level are commonly regarded as a storehouse of all kinds of energy resources but a forbidden zone for mankind or inaccessible by ordinary technologies.

With what is formally known as industrial application of drilling and completion technologies at HTHP gas fields, the China National Offshore Oil Corporation (CNOOC) Zhanjiang Branch achieved the impossible; for which it won the first prize of the National Science and Technology Award this year.

The South China Sea has one of the world's largest high-temperature and high-pressure regions on par with the Gulf of Mexico and the North Sea off England. Nearly 15 trillion tons of natural gas lie there, one third of the South China Sea's total, according to the Ministry of Land and Resources.

Researches show that the temperatures at the seabed stratum can reach 249 degrees Celsius, while the pressure there is equivalent to putting 125,000 tons on a surface of one square meter. These two hurdles are presented as insurmountable for those who want to exploit the natural resources.

Back in the 1980s, the Chinese government employed six international petroleum companies in an attempt to overcome technical difficulties. Costing 4.95 billion yuan ($770.8 million), the efforts by the world-class teams was nothing more than a gruesome wild goose chase.

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 an arduous effort of nearly 20 years, it has broken numerous technical bottlenecks to discover and access HTHP gas fields with a success rate of 100 percent.

With 11 state-of-the-art technologies in four systems, CNOOC Zhanjiang Branch can cut the average drilling period from 175 days to 52 days and reduce cost by 50 percent. At the same time, the accuracy of its pressure forecasting technique is up to 95 percent, 25 percent higher than its peers.

The technologies not only have been successfully applied to the HTHP gas fields in China, but were also adopted in eight HTHP gas fields in the Gulf of Mexico, seven in the North Sea and 18 in Iraq. So far, they have generated direct revenue of 21.6 billion yuan and indirect revenue of 356.5 billion yuan.