Feb 12 (Reuters) - The Organisation of Petroleum Exporting Countries and their allies plan to begin the unwind of its output cuts gradually in April which could completely change FX markets.

Oil which has traded heavily throughout the period that producers have limited supply could slide below the base of long established ranges, lessening inflation pressure. This will allow the Federal Reserve to lower the U.S. interest rate, potentially leading to a correction of the dollar uptrend.

The rising dollar and its influence on lesser currencies which have slumped, with a number reaching record lows, has been at the centre of activity in currency markets. There is potential for a sea change in thinking should oil drop with any pullback for the dollar relieving pressure on many emerging currencies including those of the influential BRICS nations.

Should oil slide it will also undermine the economies of larger producers and the United States is among the biggest.

During the period supply has been limited Brent crude oil has repeatedly based around $70/bbl and hasn't closed below the 100-MMA at $70.80/bbl for almost four years but crude has traded heavily.

Crude, which has been in a declining trend for several years, dropped toward $74/bbl earlier this month, bringing it close to big levels. If OPEC opens the taps as it clearly desires, trading ranges could drop substantially, perhaps $50-80/bbl from $70-100/bbl.

Should this happen, the dollar could finally undergo a meaningful correction of its 2011-2024 rise, and minor corrections of that rise equate to at least a 7% drop, and perhaps twice that.

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(Jeremy Boulton is a Reuters market analyst. The views expressed are his own)

((jeremy.boulton@thomsonreuters.com))