* First-half output 173.3 mln boe excluding Nexen's contribution
* Including Nexen's contribution, first-half output jumps 23.1 pct
* First-half net profit of 34.38 bln yuan beats analyst estimates
* First-half capex soars 34.8 percent on year to $5.21 billion (Recasts with details, comments from CNOOC executives)
HONG KONG, Aug 20 China's top offshore oil explorer CNOOC Ltd, which acquired Canadian energy firm Nexen for $15.1 billion in February, said it is on track to meet its 2013 output target after posting a first-half profit that beat analyst estimates.
CNOOC, once an investor darling for its high-growth profile, has been struggling to boost its output in the past few years as domestic fields age. The firm has spent heavily on more advanced technology to drill in deep-sea areas off the Chinese coast, expanded into unconventional energy such as oil sands and shale in North America, and acquired assets including Nexen - the biggest ever overseas corporate takeover by a Chinese company.
State-controlled CNOOC said previously it aimed to produce 338 million-348 million barrels of oil equivalent (boe) this year, excluding Nexen's contribution, or growth of just up to 2 percent from 2012. First-half output rose 7.7 percent on year to 173.3 million boe, not including Nexen's production, according to a filing with the Hong Kong stock exchange on Tuesday.
"We maintain our original production forecast," CNOOC's Chief Executive Li Fanrong told reporters at the firm's earnings briefing, adding that the company is keeping its original output target of 6 to 10 percent compound annual growth in 2011-2015, excluding contributions from Nexen.
In the filing released after the market close, CNOOC said first-half net profit gained 7.9 percent to 34.38 billion yuan ($5.61 billion) as increased output offset lower crude prices and higher operating costs. That topped the average forecast of 30.87 billion yuan in a Reuters poll of four analysts.
Nexen contributed 197 million yuan to CNOOC's net profit and 24.8 million boe to the firm's output.
For the whole of this year, Nexen is expected to contribute 59 million boe to CNOOC's output, Chief Financial Officer Zhong Hua said at the briefing.
CNOOC said previously that the acquisition of Nexen would boost its output by 20 percent and increase its proven reserves by 30 percent.
"We bought Nexen not because we expected any immediate benefit. We are looking at its long-term potential," Li said.
Shares of CNOOC ended 1.72 percent lower at HK$14.82 on Tuesday, outperforming a 2.2 percent decline in the blue-chip Hang Seng Index.
However, in the first half of the year, the stock underperformed compared with the shares of other Chinese oil majors such as PetroChina. That was partly due to investor concerns that CNOOC overpaid for Nexen, analysts say.
Excluding contributions from Nexen, production rose in the first half as CNOOC's Penglai 19-3 oilfield in eastern China's Bohai Bay resumed output after an oil spill in 2011. Projects in the United States and Iraq were also "an important source of production growth," CNOOC said.
CNOOC aims to launch 10 new exploration and production projects offshore China in the second half. But the projects will have limited impact on this year's output and earnings as most of them won't be up and running until the end of 2013, company executives said.
Increased exploration has come with higher expenses.
Capital expenditure soared 34.8 percent on year to $5.21 billion in the first half. CNOOC, which held 48.1 billion yuan cash on hand at the end of June, has earmarked capital expenditure of $12 billion-$14 billion for the entire 2013.
That excludes Nexen's 2013 spending of $3.16 billion.
CNOOC, which declared an interim dividend of HK$0.25 per share for the first half, said its integration with Nexen was proceeding smoothly, and that CNOOC has been "actively" working on its application for a secondary listing on the Toronto Stock Exchange.
To win Canadian approvals for the Nexen takeover, CNOOC made a series of commitments like retaining all Nexen staff, pursuing a listing in Toronto, and making Calgary the headquarters of its $8 billion North and Central American operations. ($1 = 6.1229 Chinese yuan) (Reporting by Charlie Zhu; Additional reporting by Twinnie Siu and Christina Lo; Editing by Ryan Woo)