"The export schedule for the first quarter of 2024 is lower than for October-December", one of the sources said.

The quarterly export schedule is a three-month export plan for Russian oil companies issued ahead of a new quarter allowing them to plan supplies via pipeline monopoly's Transneft system.

"We estimate Russia's average seaborne oil exports at 3.5 million bpd so far in December, in January we expect it to fall due to increased refining", said Viktor Katona, senior oil market analyst at Kpler consulting.

Russia's offline primary oil refining capacity for December has almost tripled from previous plans to 2.098 million metric tons as some refineries reviewed their maintenance plans.

"The average throughput at oil refineries in Russia was at 5.5 million bpd in October and last week it increased to 5.7 million bpd", Katona added.

The three sources expect oil loadings to decline mainly in Russia's western ports, Primorsk, Ust-Luga and Novorossiisk, where the supply swap with refineries is technically easy.

The December exports from these ports may be higher than planned 1.9 million bpd due to rollover of some cargoes from November, when the Black Sea shipments had been disrupted by a storm.

Russia has promised to deepen the voluntary cuts of oil and products exports under OPEC+ cooperation agreement in the first quarter of 2024 by 200,000 bpd to 500,000 bpd.

The reduction is calculated based on the average level of Russian exports for May and June 2023. According to Russian Deputy Prime Minister Alexander Novak, Russia has already begun to cut supplies in December.