Oct. 14 (Bloomberg) -- Cnooc Ltd., China's biggest offshore oil producer, rose the most in almost a month in Hong Kong trading as crude oil prices climbed for a second day.

Shares of the state oil company gained 14 percent to HK$7.17, the most since Sept. 19. Cnooc was the sixth-largest gainer on the 40-member MSCI AC Asia Energy Index. The benchmark Hang Seng Index climbed 3 percent.

Oil headed for its biggest two-day gain in three weeks as stock markets climbed after the U.S. and European governments agreed to buy stakes in banks to avert a collapse in the financial markets. Crude oil for November delivery rose as much as 4.1 percent to $84.53 a barrel in after-hours electronic trading on the New York Mercantile Exchange.

``$80 a barrel is the glass floor and we doubt oil can trade down below this level for a sustained period of time without forcing supply destructions and creating cross-border strategic mergers and acquisition opportunities,'' Gordon Kwan, an analyst at CLSA Ltd., said in a research note today.

Cnooc's share advance outpaced a 3 percent gain at bigger rival PetroChina Co. and a 3.7 percent increase at China Petroleum & Chemical Corp., Asia's largest refiner. Higher oil prices will boost costs at PetroChina, which has refining operations, and Sinopec, as China Petroleum is known.

Cnooc's first-half profit climbed 89 percent to a record 27.54 billion yuan ($4 billion), helped by higher output and a 46 percent jump in oil prices, the company said in August.

CLP, Hongkong Electric

Crude oil has fallen more than 40 percent from a record $147.27 a barrel reached in July. It was at $84.25 a barrel at 9:16 a.m. London time. Oil has climbed 7.3 percent in the past two days, the most since Sept. 22.

Shares in CLP Holdings Ltd. and Hongkong Electric Holdings Ltd., the city's two main utilities, fell after some investors switched out of so-called defensive stocks in favor of companies with higher returns as the market rebounds, Michael Yuk, an analyst with Sun Hung Kai Securities, said by phone from Hong Kong.

CLP fell by 6.3 percent to HK$55.30. Hongkong Electric, controlled by billionaire Li Ka-shing, retreated 6.8 percent to HK$43.80. Hong Kong & China Gas Co. shares dropped 2 percent to HK$15.20.

To contact the reporter on this story: Wang Ying in Beijing at ywang30@bloomberg.net

Last Updated: October 14, 2008 05:20 EDT