PARIS - Oil prices are expected to keep sliding well into 2015, held down by weak demand and increased shale production, the International Energy Agency said Friday. Global prices have collapsed by some 30 percent since June, and crude futures slumped on Thursday to lows not seen since September 2010, diving well below the $80-per-barrel mark. The IEA said while there had been speculation that the high cost of shale extraction “might set a new equilibrium for Brent prices in the $80 to $90 range, supply/demand balances suggest that the price rout has yet to run its course”. “Our supply and demand forecasts indicate that barring any new supply disruption, downward price pressures could build further in the first half of 2015,” it added.

Prices were unlikely to reverse course anytime soon, as there are “deep structural changes” transforming the industry.

China, which in recent years has had a voracious appetite for energy, is now entering a less oil-intensive stage of growth, while technological innovations have unlocked shale resources in North America.

“A return to previous price highs may not be a close prospect, as it is increasingly clear that we have begun a new chapter in the history of the oil markets,” the IEA said.

Dealers were also betting that the 12-nation OPEC cartel, which is meeting on November 27 in Vienna, would decide against cutting output quotas.

This is because OPEC is battling to maintain its foothold in the US market against the flood of oil being extracted domestically from shale rock — which had in part caused the global glut.

- ‘It’s purely business’ -

As pressure mounts on OPEC to slash output, Ali Al-Naimi, oil minister of the cartel’s kingpin Saudi Arabia, said that “talk of a price war is a sign of misunderstanding — deliberate or otherwise — and has no basis in reality”.

“We do not seek to politicise oil, nor do we collude against anybody. For us, it is a question of supply and demand. It is purely business,” he said on Wednesday.

In a report to the G20 group of leading industrial powers ahead of a summit in Brisbane this weekend, the International Monetary Fund said the “recent appreciable fall in oil prices, if sustained, will boost growth”.

But the lower prices are hurting some crude exporters, including Venezuela, Iran and Russia. The latter two are also struggling with the impact of Western sanctions.

The IEA noted that production at current or even lower prices may not be uneconomical, but “it may take a toll on social stability and thus indirectly affect production prospects”.

Prices had touched a high in June of $115.71, when the Islamic State organisation’s offensive in Iraq had pushed up costs. But abundant supplies, tepid demand and the strong dollar have forced them back down.

Supply growth also shows few signs of abating. On Thursday, US production hit a new record.

The world is awash in oil even as both Iraq and Libya — the two countries responsible for OPEC’s recent recovery in supply growth — are both in the throes of conflicts.

Demand growth is meanwhile expected to remain at the five-year low rate of 680,000 barrels a day in 2014, reaching an estimated 92.4 million barrels a day, the IEA said.

“Relatively weak Chinese demand growth, coupled with large absolute declines in both European and OECD Asia Oceania, curb the upside momentum otherwise provided by gains in other non-OECD economies and the US,” it said.

Accelerating global momentum is seen lifting demand growth to reach 1.1 million barrels a day to 93.6 million barrels a day.

Oil prices rebounded slightly on Friday, although they remain well below $80. Brent crude for January gained 70 cents to $78.19 per barrel in late morning London deals, while US benchmark West Texas Intermediate (WTI) for December rose 13 cents to $74.34.