CNOOC Reports Gas Find in Bohai Sea

China National Offshore Oil Corp. (CNOOC), the country’s main offshore energy producer, has made a natural gas discovery at its first well in the Bohai Sea deeper than 5,000 meters (m), CNOOC announced on Thursday.

CNOOC drilled the Bozhong 21-2-1 well to a depth of 5,141 m over a period of 105 days, ending in June, according to the announcement. The discovery marks the first time that China has found gas in the Bohai Sea at a depth greater than 4,000 m since 1965.

The successful drilling of the well is a “breakthrough” and the experienced gained by CNOOC will benefit its deepwater exploration programme elsewhere, Hao Jianying, an engineer with CNOOC’s Science and Technology Development Department, told Interfax on Thursday.

CNOOC will need to drill more wells for tests and determine if further development will be commercially viable, according to Hao.

The discovery is the latest in a string of finds over the past few months for CNOOC, which is moving into deepwater areas to boost production. The state-owned major’s listed vehicle, CNOOC Ltd., announced in April the discovery of Dongfang 13-2, a high-temperature, high-pressure gas reservoir in the Yinggehai Basin of the South China Sea. The offshore find was in the central sag of the basin, with gas flow rate from a 3,168 m discovery well averaging 1.2 million cubic meters per day.

It may take CNOOC Ltd. more than five years to start commercial production at Dongfang 13-2, Chief Financial Officer Zhong Hua said in a conference call in April.

That find was followed by an announcement on May 24 that CNOOC’s Luda 21-1 discovery well had encountered oil after being drilled to a depth of 2,831 m, in waters with an average depth of 20 m.

Gas from Bozhong 21-2-1 consisted of 53 percent carbon dioxide, CNOOC said. The concentration of carbon monoxide was higher than 1,000 milligrams per liter (mg/l), while hydrogen sulphide concentration was in excess of 250 mg/l.

The presence of hydrogen sulphide is undesirable as gas from the well will need to be ‘sweetened’ to remove the sulphur content, Hao said. (Interfax, Edited by Topco)