AFP examines the outlook on fully restarting Gulf oil and gas production, some of which is forecast to take years.

- Huge damage -

Since the start of the conflict in the Middle East at the end of February, more than 150 attacks have targeted energy sites in the region, including nuclear ones, according to an AFP estimate based on data from the American NGO Acled.

Among them, at least 44 facilities linked mainly to oil and gas -- depots, refineries and extraction fields -- have suffered damage, as well as a dozen energy transport sites.

The cost of repairing the infrastructure could be between $34 billion and $58 billion, according to an estimate from Rystad Energy.

Its most severe scenario forecasts that the bill for fixing oil and gas facilities alone could reach $50 billion.

If the ceasefire is not extended, "the long-term consequences of the war will be more serious", Arne Lohmann Rasmussen, an analyst at Global Risk Management, told AFP.

Liquefied natural gas (LNG), as well as certain petroleum products such as kerosene or diesel, are particularly exposed to shortages, he added.

- 'Prices to stay high' -

The key to returning to normal production remains the reopening of the Strait of Hormuz, through which approximately 20 percent of global oil and LNG production was transported before the war and a near halt to flows.

But even a reopening of the waterway would not allow an immediate return of all barrels to the market.

"It could take months, or even longer," Saxo Bank analyst Ole Hansen of Saxo Bank told AFP.

"The process of restoring flows is unlikely to be smooth," he said, pointing to tankers being out of position as well as dislocated supply chains.

Production is unable to resume until the storage tanks in which the Gulf countries have had to store their oil "have been sufficiently drawn down", Hansen said.

"In the last seven weeks, the world has lost more than 500 million barrels of production," the analyst pointed out, adding that the strategic reserves of importing countries, which have been dipped into during the war, will have to be restocked.

These factors combined should keep oil prices elevated, possibly between $80 and $85 a barrel, compared with around $70 pre-war, Hansen estimated.

- 'Uneven restart' -

Should oil production resume, "about 70 to 80 percent of supply can return within weeks", noted Homayoun Falakshahi, an analyst at energy intelligence firm Kpler.

For the remaining amount, restarting output is a more challenging and therefore should take longer, he said, pointing to differences among producing Gulf nations.

"In Saudi Arabia and the United Arab Emirates, things can go pretty quickly. They can restore their production in a few weeks," Falakshahi told AFP.

In Iraq and Kuwait, however, a return to normal could take several months owing to their oil being heavier and therefore harder to prepare for the international market.

Total restoration of production capacities in Iran and Qatar could meanwhile take years.

"Iran accounts for the highest number of impacted facilities and the widest spread across asset types, with repair costs potentially reaching up to $19 billion under a high-damage scenario," estimated Rystad Energy.

In Qatar, the region's main LNG exporter, gas infrastructure has mainly been impacted.

State-owned QatarEnergy said on March 20 that it had lost 17 percent of its export capacity, with repairs likely to last up to five years after missile attacks on its Ras Laffan complex, the world's largest LNG production site.