Oil price rebound in focus but gloom gathering

Oil prices were being closely watched Wednesday after a rally in the previous session, ahead of crucial U.S. crude stockpile data due out later in the day. But seasoned market watchers say investor optimism of a rally is unfounded - for now.

On Tuesday, the price of benchmark Brent crude and U.S. sweet crude for December delivery closed more than 3 percent higher, at $50.54 and $47.90 respectively, after having surged more than 4 percent at one point in the trading session.

Prices were supported by fears of supply disruptions in Brazil and Libya, following a strike at state-run oil producer Petroleo Brasileiro and the closure of a Libyan oil export terminal.

On Wednesday, prices had slipped slightly on profit-taking, with Brent trading at $50.33 and U.S. crude at $47.76 and investors were looking ahead to U.S. government inventory data.

The latest information on U.S. crude oil stockpiles is due to be released by the Department of Energy (at 10:30 a.m.ET) and could put a further dampener on sentiment.

U.S. commercial crude oil stocks are expected to have increased 2.45 million barrels in the week ended October 30, a Platts survey of analysts showed Monday. On Tuesday, industry group American Petroleum Institute suggested a build in stockpiles of 2.8 million barrels last week.

Aside from the suspected build in U.S. stockpiles, there is still no sign that production is slowing from major oil producers such as OPEC, the Organization of Petroleum-Exporting Countries (OPEC).

Despite a sharp decline in oil prices from a high of $114 a barrel in June 2014 to their current level, OPEC, which is led by Saudi Arabia, has refused to cut production levels (which would support prices) and has regularly exceeded its 30 million barrels a day ceiling.

Read More Oil slump sends Saudi Arabia's PMI to all-time low

The strategy has been seen as a way to defend its market share against competition from U.S. shale oil producers, who have higher production costs. The move appears to have worked with many producers stateside halting production, investment and cancelling drilling projects.

Tim Evans of Citi Futures said Tuesday that the rally in prices was another example of the triumph of hope over experience, and OPEC would not be acting to support prices any time soon.

"The oil market continues to reflect an enduring optimism that the reduction in non-OPEC investment of the past year will be sufficient to rebalance the market and support at least some degree of upward correction in prices," said Tim Evans of Citi Futures in a note Tuesday.

Read More Oil demand growth to slow, IEA says, but is OPEC listening?

"What's missing from this analysis, in our view, is recognition that OPEC production continues to exceed the call on OPEC crude and that added production from Iran would sustain and extend this supply/demand surplus through 2016," he said.

Evans expressed surprise that "the market also seems to view the prospect of a build in U.S. crude stocks for last week as no particular obstacle to a move higher."

Oil market analysts elsewhere are also optimistic that prices can recover. On Monday, UBS' 2016-2017 global outlook report assumed an average Brent crude oil price of $57.50 a barrel (with WTI at $52.50) and there is optimism within the energy industry too.

Alex Schneiter, chief executive of Lundin Petroleum, told CNBC Wednesday that the Swedish oil and gas company didn't expect prices to fall again in 2016.

"Ninety percent of our business is oil, as a starting point, and personally we see now a lot of under-investment…but I think it's not going to be very different from any other cycles, you'll see that the supply side will reduce and the demand side has so far been strong."

"So I foresee that in time there will be a recovery, the timing exactly is maybe more difficult to call but I think it'll be sometime towards the second half of 2016."

- By CNBC's Holly Ellyatt, follow her on Twitter @HollyEllyatt.

More From CNBC

• Top News and Analysis
  

• Latest News Video
  

• Personal Finance