When the futures market shows near-dated oil contracts trading above those further out, a pricing structure known as backwardation emerges, which indicates that traders believe supply is becoming restricted and encourages anyone storing up physical oil to release their stocks.
Mr Barkindo said consultations were under way for the extension of the OPEC-led pact beyond March 2018 and that more oil producing nations may join the supply pact, possibly at the next meeting of OPEC in Vienna on November 30.
OPEC and other oil producers may need to take "some extraordinary measures" next year to rebalance the oil market, the OPEC secretary-general said on Sunday. "Between the first half and second half this year, demand growth is nearly about 2 million barrels (per day), which is very robust", he said.
The 14-country producer group said its oil output in September, as assessed by secondary sources, came in below the demand forecast, even though output climbed slightly.
OPEC, along with other producers including Russian Federation, agreed to cut output by 1.8 million barrels per day (bpd) through March 2018 to balance the market.
Increasing demand for oil will be matched by added supplies, but Opec's forecasts for the balance of supply and demand foresee a greater reliance on the cartel's output.
OPEC's reluctance to cut output was also seen as a key reason behind the fall.
Oil prices tumbled from over $100 in 2014 after OPEC nations led by Saudi Arabia cranked up production to try to push out United States shale producers which have higher production costs.
However it doesn't see prices climbing soon.
Brent crude, the benchmark for more than half of the world's oil, was little changed at $55.32 a barrel by 10:43 a.m.in London.
Oil prices have been rising since the end of summer, but remain well below their 2014 level.
If OPEC does decide to extend the agreement, oil prices should at the very least, hold firm, and could easily build on recent gains through the remainder of the years.
A sharp increase in oil prices would tend to discourage consumption and thus growth.