What can the world expect from the forthcoming Vienna meeting of oil producing nations?

Opec and its friends can be divided up in many ways, but the most useful in the current environment is the “Haves” and the “Have Nots.”

The first group consists of Russia, Saudi Arabia and the other countries of the Arabian Peninsula, who have the spare capacity to raise production if they wish. The rest fall into the other camp, with little, or no, ability to raise production.

Why does this matter? Because Saudi Arabia and Russia are trying to assemble support for lifting the group’s output. They are likely to find some allies, but face opposition led by Iran and Venezuela.

This means Opec’s June 22 meeting is likely to be stormy. Both Venezuela and Iran have written to the group urging unity against external sanctions, citing Article 2 of its statute, something I identified last week as potentially driving negotiations. Their move is unlikely to sway Saudi Arabia, which is facing growing US pressure for a million-barrel-a-day increase in supply, or Russia, where the oil industry is urging restraint to be eased.

If anything gets agreed at all, it may simply be to maintain the current deal on paper while committing to ensure adequate supply to the market – that would be vague enough to cover just about any eventuality without directly addressing any of them.

Opec is already forecasting a big global oil deficit for the second half of 2018. This assumes that the group continues to produce as much oil as it did last month. But if supply from Venezuela and Iran falls, that deficit will get even bigger.