OPEC's campaign to cut global oil supplies is working

The International Energy Agency said Friday that OECD oil stockpiles are almost down to their five-year average.

Why it matters: That's the original goal of the production-limiting deal between OPEC, Russia and some other producers seeking to clear the global glut.

The IEA's new monthly oil market report states:

• "With markets expected to tighten, it is possible that when we publish OECD stocks data in the next month or two they will have reached or even fallen below the five-year average target."
• "It is not for us to declare on behalf of the Vienna agreement countries that it is 'mission accomplished', but if our outlook is accurate, it certainly looks very much like it."

OECD stocks has fallen to just 30 million barrels above their five-year average at the end of February, IEA said.

But, but, but: The goals and status of the OPEC-Russia relationship has become an evolving thing as the producers grapple with the rise of U.S. shale and seek to continue propping up prices. It's unlikely they'll seek an early exit to the current agreement that's slated to run through year's end.

• "Despite shrinking oil inventories, Opec producers have said alternative metrics must be considered when evaluating the success of the deal and how long cuts should be maintained," the Financial Times noted Friday.

And there are also plans for a longer term — maybe much, much longer term — collaboration on market management between OPEC and Russia.

One level deeper: "OPEC appears to be reformulating its target in terms of upstream investment rather than oil inventories, according to an analysis of recent statements made by ministers from member countries," Reuters analyst John Kemp wrote Thursday.

For now IEA is sticking with its forecast of 1.5 million barrels per day of demand growth this year to reach 99.3 million, but warns, "the trade dispute between the US and China is introducing a downward risk to the forecast."

Go deeper: The Wall Street Journal has more on how trade fights could hit oil forecasts.