"Russia's oil exports are entering a new phase of disruption as sanctions targeting Rosneft and Lukoil are set to take effect, prompting its two largest customers — India and China — to sharply reduce their December purchases," the Wall Street bank said in a note, as carried by Reuters.

According to JPMorgan's estimates, as many as 1.4 million barrels per day (bpd) of Russian crude oil, or nearly a third of its exporting potential, are on tankers at present, amid re-routing and slowed unloading as buyers are hesitant following the U.S. sanctions on Russia's top oil producers and exporters, Rosneft and Lukoil. 

Due to the sanctions, the discount of Russia's flagship crude Urals to Brent has widened in recent days to the highest this year at $20 per barrel. 

As of Monday, Urals was priced $19.40 per barrel below Brent on a free-on-board (FOB) basis at the Russian Baltic Sea port of Primorsk and at the port of Novorossiysk on the Black Sea, widening from $13-$14 per barrel discount at the beginning of November, an industry source told Russian daily Kommersant earlier this week, citing data by Argus.  

All but two Indian refiners have skipped placing orders for Russian crude for December after the U.S. sanctioned Rosneft and Lukoil, sources with knowledge of the purchases told Bloomberg earlier this week.  

In China, major state-owned refiners have reportedly suspended purchases of Russian crude oil, but the independent refiners in the Shandong province, the so-called teapots, are unlikely to halt imports of the cheap crude that has become a staple for their refineries.