Brent crude LCOc1 settled down 22 cents, or 0.6%, at $39.61 a barrel while U.S. West Texas Intermediate (WTI) crude futures CLc1 were down 7 cents, or 0.2%, at $37.26 a barrel.
Both crude oil contracts ended lower in the previous week, its second consecutive week of decline.
Hurricane Sally gained in strength in the Gulf of Mexico, west of Florida on Sunday and was poised to become a category 2 hurricane.
Persistent damage to the global economy from the coronavirus pandemic will hollow out demand for oil more than previously thought, major industry figures said on Monday. OPEC said it now expects world oil demand to grow by 6.6 million barrels a day to 96.9 million barrels a day in 2021, around 400,000 barrels a day below its previous forecast.
Production of liquid hydrocarbons in Russian Federation (oil and condensate) in August increased by 0.49 million barrels per day in monthly terms, to 9.97 million barrels per day.
Meanwhile, OPEC, which painted a gloomy picture of the market, has stated: "In 2020, the global oil demand contraction is revised down further by 0.4 mb/d, now contracting by 9.5 mb/d, to average 90.2 mb/d".
The Organization of Petroleum Exporting Countries (Opec) downgraded its outlook for the global oil market a few days before ministers meet, amid faltering demand and signs of a recovery in supply from U.S. shale drillers. The lifting of the blockade would add more supplies to the market, but Haftar's statement did not specify whether oil fields and ports would also recommence operations.
"If Libya's production comes back online soon, we are talking about 1 million barrels per day or more, this will be a significant addition to the global balances".
Stephen Innes, Chief Global Market Strategist at AxiCorp, in a note to Nairametrics, gave insights into the fundamentals, keenly monitored by oil traders.