OREANDA-NEWS. November 19, 2014. CNOOC Group Ltd, China's largest offshore oil and gas developer, announced that its semi-submersible drilling rig Nanhai Jiu Hao completed the first deep-water exploration well in the South China Sea.

Nanhai Jiu Hao became the second deep-water drilling rig after CNOOC 981, which shows that China now has the technology and equipment to carry out large-scale oil and gas exploration in deep-water areas, said the company.

The well, Lingshui 25-1-1, is located in the Qiongdongnan Basin with a depth of 3,930 meters, according to the company. More work needs to be done to verify the well's resources.

Huang Benhui, who works on Nanhai Jiu Hao, said the South China Sea is notorious for tough operating conditions, but the rig has advanced features that will allow it to cope with the bad weather.

The rig has already drilled six exploration wells in the South China Sea, he said.

China Oilfield Services Ltd, owned by CNOOC, is the operator of the rig. The company manages 43 drilling platforms, two accommodation platforms and four modularized drilling rigs.

Yuan Xiaosong, deputy general manager of COSL's drilling segment, said that more than 20 drilling platforms are working in China. The rest are operating at the company's overseas projects.

"Nanhai Jiu Hao will boost the country's offshore oil and gas exploration by teaming up with CNOOC 981 to work in different sea areas at the same time, which can improve the efficiency of the country's offshore oil and gas drilling," Yuan said.

CNOOC 981, the largest and first deep-water drilling rig in China, can function in depths of about 3,000 m, though it is usually used at depths of 800 to 1,500 m. The best choice for deeper projects is Nanhai Jiu Hao, which is more cost-efficient than CNOOC 981, Yuan said. Nanhai Jiu Hao's maximum operational depth is 1,524 m.

"Nanhai Jiu Hao will keep working in the South China Sea for domestic operations. It may also be used overseas if there is a need," he said.

According to CNOOC, the rig has been used in Norway and western Africa. It is 99 m long, 88 m wide and 116 m high.

In September, CNOOC 981 reported its first deep-water gasfield discovery - the Lingshui 17-2 field below the South China Sea and 150 km south of Hainan Island.