* Nikkei still seen rangebound, capped by investors' profit-taking
* Oil company shares jump as crude oil futures rally
TOKYO, Sept 29 (Reuters) - Japan's Nikkei share average rose more than 1 percent on Thursday as investors took heart from a weaker yen and rallying oil prices after OPEC's unexpected agreement to trim crude output.
The Nikkei stock index was up 1.4 percent at 16,699.18 at the end of the morning session.
The Organization of the Petroleum Exporting Countries agreed on Wednesday to limit its production to a range of 32.5-33.0 million barrels per day (bpd) in talks held on the sidelines of an energy conference in Algeria.
The news sparked a rally on Wall Street, and the buoyant mood carried over into Asian trading.
"The OPEC move was a surprise, and left some hedge funds scurrying to cover their short positions," said Norihiro Fujito, a senior investment strategist at Mitsubishi UFJ Morgan Stanley Securities in Tokyo.
But he said the Nikkei was likely to remain rangebound.
"On any move above 16,700, there are institutional investors ready to take profits, and on the downside, there is the perception that Bank of Japan buying will come in on moves below 16,500 and support the market."
The OPEC news lifted shares of Japanese oil companies, with Inpex Corp rising as much as 7.9 percent, Japan Petroleum Exploration (Japex) up as much as 9.8 percent and Cosmo Energy Holdings gaining as much as 4.6 percent.
The oil and coal subindex was up 3.1 percent.
News that Hitachi Ltd, Toshiba Corp and Mitsubishi Heavy Industries Ltd aim to merge their nuclear fuel businesses had little overall market impact, amid bleak prospects for Japan's atomic reactors to return to operation after the Fukushima disaster.
Shares of Japan's Sega Sammy Holdings jumped 2.8 percent after touching a more than one-year high after the gaming company more than doubled its half-year profit outlook.
A weaker yen also helped lift sentiment. The dollar rose 0.6 percent against the Japanese currency to 101.34 yen, pulling away from Tuesday's one-month low of 100.085. The euro added 0.8 percent to 113.79 yen.
The broader Topix rose 0.9 percent to 1,343.16.
The JPX-Nikkei Index 400 added 1 percent to 12.027.85. (Reporting by Tokyo markets team; Editing by Kim Coghill)