COMMODITIES-Range-bound trade in oil,most markets; natgas spikes

* CRB index virtually unchanged for 2 day

* Brent crude ends up 6 cents after doubts on oil demand

* Metals in quite trade ahead of G20 meeting

* Natgas jumps 2 pct on forecasts for cold U.S. weather

* Grains markets see little price change

NEW YORK, Feb 13 (Reuters) - Most commodities were trapped in range-bound trading for a second straight day on Wednesday, with oil hampered by doubts over demand and metals affected by caution ahead of a meeting of world finance ministers and central bankers. Natural gas was an exception, rallying more than 2 percent on expectations for a bullish inventory report from the U.S. government on Thursday. Forecasts for colder U.S. weather in the next two weeks helped underpin the run-up. A handful of commodities from orange juice to aluminium and raw sugar rose about 1 percent, extending their trend higher or rebounding from a recent slump.

MOSTLY ANEMIC PRICE ACTION Others saw anemic price action. Oil, copper and gold moved less than half a percent each. Grains markets also saw little price change despite corn falling for a ninth straight session on improving crop weather in South America; wheat rebounding from a seven-month low and soybeans recovering from a one-month bottom. The Thomson Reuters-Jefferies CRB index, a global benchmark for commodities, settled virtually unchanged for a second straight day, with 10 of the 19 markets it tracks ending in positive territory.

ON GUARD AHEAD OF G20 Traders said investors were mostly on the guard with the dollar trading steady ahead of the two-day meeting of the Group of 20 developed and emerging market economies in Moscow beginning Friday. Exchange rates are expected to be a hot topic at the G20 meet and any dollar strength is expected to weigh on demand for commodities denominated in the U.S. currency. "Although people are not expecting anything dramatic to be said at the G20 meeting, there is still some uncertainty, which may see short-term investors cover their short positions in coming sessions," Societe Generale analyst Robin Bahr said.

GAS RALLIES ON COLD U.S. WEATHER Front-month gas futures in New York ended up 7.6 cents, or 2.4 percent, at $3.306 per million British thermal units. Gas prices this year have mostly been stuck in a trading range between $3.20 and $3.60 per mmBtu. But recent tests of support have held and may continue to do so if U.S. Northeast and Midwest temperatures turn colder later this week and kick up demand for gas to heat homes and businesses. "A lot of the buying had to do with the temperature outlook which looks pretty cold, but the market is still range-bound," said Aaron Calder, analyst at Gelber & Associates in Houston. Traders said current gas prices were low enough to prompt utilities to switch from coal to gas to generate power, while hefty nuclear plant outages this week of more than 13,000 megawatts could boost gas demand further. Gas-fired units are typically used to offset any shut nuclear generation. Traders and analyst polled by Reuters also expect the U.S. Energy Information Administration (EIA) to announce a significant drop in gas inventories when the government-run agency releases its weekly storage report on Thursday.

OIL DOWN ON STOCKPILE BUILD In oil, benchmark Brent crude in London rose 6 cents to close at $118.72 a barrel, with gains were capped by a rise in weekly U.S. oil inventories. U.S. crude inventories rose by 560,000 barrels in the week ending Feb. 8, the EIA said in a report on U.S. crude stockpiles issued a day before its report on gas inventories. The inventory build in the world's largest oil consumer weighed on prices of the New York-traded U.S. crude, which closed down 50 cents at $97.01 a barrel. "The underlying supply and demand fundamental picture really hasn't changed. We have a lot of oil here in the United States," said Gene McGillian, analyst at Tradition Energy in Stamford, Connecticut.

Prices at 5:11 p.m. EST (2211 GMT)

LAST/ NET PCT YTD CLOSE CHG CHG CHG US crude 97.17 -0.34 -0.4% 5.8% Brent crude 118.75 0.09 0.1% 6.9% Natural gas 3.306 0.076 2.4% -1.3%US gold 1644.20 -4.50 -0.3% -1.9% Gold 1642.09 -0.06 0.0% -1.9% US Copper 374.25 -0.15 0.0% 2.5% LME Copper 8226.00 -10.00 -0.1% 3.7% Dollar 80.065 -0.041 -0.1% 4.3%US corn 695.50 -0.75 -0.1% -0.4% US soybeans 1423.00 2.25 0.2% 0.3% US wheat 735.50 3.50 0.5% -5.5%US Coffee 138.75 -1.90 -1.4% -3.5% US Cocoa 2143.00 -36.00 -1.7% -4.2% US Sugar 18.23 0.15 0.8% -6.6%US silver 30.869 -0.150 -0.5% 2.1% US platinum 1728.60 12.50 0.7% 12.3% US palladium 772.05 0.65 0.1% 9.8%