HONG KONG Jan 20 (Reuters) - Top Chinese offshore oil and gas producer CNOOC Ltd said on Monday it is aiming for an up to 4.3 percent increase in output this year, excluding contributions from Canadian oil producer Nexen it acquired a year ago.
CNOOC also said it has earmarked 105 billion to 120 billion yuan ($17.35 billion to $19.83 billion) in total capital spending for exploration, development and production for this year, with Nexen accounting for about 19 percent.
The state-run company plans to produce 353 million-366 million barrels of oil equivalent (boe) this year, excluding Nexen output, compared with estimated output of 351 million boe in 2013, it said in a filing with the Hong Kong stock exchange.
The 2013 output estimates were above the company's target of 338-348 million boe.
CNOOC acquired Nexen for $15.1 billion in March 2013 in China's biggest foreign corporate takeover.
Including Nexen's output, CNOOC aimed to produce 422-435 million boe this year, up from 412 million boe estimated for 2013.
CNOOC, once an investor darling for its high-growth profile, has struggled to boost its output the past few years as domestic fields age. It has invested in deepwater technology to drill in frontier areas off China's coast and expanded into unconventional energy such as oil sands and shale in North America.
Shares of CNOOC ended up 0.72 percent on Monday ahead of the announcement. The stock lost about 13 percent over the last 12 months due to worries about its production growth prospects and the premium it paid to acquire Nexen, making it the worst performer among the world's major exploration and production companies in the period.
($1 = 6.0502 Chinese yuan) (Reporting by Charlie Zhu; Editing by Tom Hogue)