Unaudited third-quarter oil and gas sales revenue for CNOOC Ltd, the largest offshore oil and gas developer in China, reached 56.14 billion yuan ($9.23 billion), a 15.9 percent year-on-year increase, the company announced on Thursday.

It said the performance benefited greatly from the growth in production.

During the quarter, the firm's net production rose by 17.8 percent year-on-year to 103.4 million barrels of oil equivalent, with Nexen Inc contributing 16.1 million BOE.

Excluding Nexen's contribution, net production for the quarter was basically flat compared with the same period last year, the company said.

"I'm glad to see that the company made significant progress in exploration in the third quarter," said Li Fanrong, chief executive officer.

The company made five new discoveries and successfully appraised 15 wells in the third quarter. Offshore, it made two new discoveries and 10 successful appraisals, while overseas, it made three new discoveries and five successful appraisals.

On Sept 18, CNOOC was listed on the Toronto Stock Exchange, signifying the company's commitment to transparency and good corporate governance.

Excluding the Nexen impact, the firm's capital expenditure was about 17.7 billion yuan in the third quarter, up by 18.2 percent year-on-year, mainly attributed to an increase in development projects. For the third quarter of 2013, Nexen's capital expenditure was approximately 4.7 billion yuan.

The company's average realized oil price increased by 1.5 percent year-on-year to $106.26 a barrel while its average realized gas price fell by 6.9 percent year-on-year to $5.43 per 1,000 cubic feet.