Russia's Energy Minister Alexander Novak, Saudi Arabia's Energy Minister and OPEC conference president Khalid al-Falih, and OPEC Secretary General Mohammad Barkindo attend a meeting of the Organization of the Petroleum Exporting Countries (OPEC) and non-OPEC producing countries in Vienna, Austria, May 25, 2017.

OPEC raised its forecast on Monday for demand for its oil in 2018 and said its deal with other producers to cut output was reducing excess oil in storage, potentially pushing the global market into a larger deficit next year.

The Organization of the Petroleum Exporting Countries also said in a monthly report it had cut its estimate of 2018 supply from non-OPEC producers and said oil use would grow faster than previously thought due to a stronger-than-expected world economy.

"The global economic growth dynamic has continued its broad-based and relatively strong momentum," OPEC said. "The ongoing momentum could still provide some slight upside potential."

OPEC said the world would need 33.42 million barrels per day (bpd) of OPEC crude next year, up 360,000 bpd from its previous forecast and marking the fourth consecutive monthly increase in the projection from its first estimate made in July.

The report is OPEC's last before a Nov. 30 meeting in which the group and its allies are expected to extend their supply-cutting deal further into next year. The projections pointing to a growing 2018 supply deficit could influence debate on how long to maintain the curbs.

Oil prices, which are close to their highest since 2015, rose further towards $64 a barrel after the report was issued. Crude is still about half its level of mid-2014 when a build-up of excess supply led to a price collapse.

The 14-country producer group said its oil output in October, as assessed by secondary sources, was below the 2018 demand forecast at 32.59 million bpd, a drop of about 150,000 bpd from September.

The report's OPEC production figures mean compliance with the supply cut by the 11 members with output targets has risen above 100 percent from 98 percent initially reported in September, according to a Reuters calculation.

"The high conformity levels of participating OPEC and non-OPEC producing countries ... have clearly played a key role in supporting stability in the oil market and placing it on a more sustainable path," the report said.

In a further sign supply excess is easing, OPEC said inventories in developed economies declined by 23.6 million barrels in September to 2.985 billion barrels, 154 million barrels above the five-year average.

"The excess overhang has fallen considerably," said OPEC, which aims to reduce stocks to the five-year average through the supply-curbing deal.