SINGAPORE: Brent crude's premium to Dubai quotes rose on Friday to the highest in 21 months on the back of stronger demand this summer, effectively keeping Atlantic Basin grades out of Asia's reach, according to traders and Refinitiv data.

Front-month August Brent crude futures' premium to Dubai quotes, or the Exchange of Futures for Swaps (EFS), rose to $3.90 a barrel, the highest since September 2019, Refinitiv data showed. The wider price spread between the regional benchmarks drives Asian demand for Middle East and Russian grades priced off Dubai quotes while making it harder for Atlantic Basin grades to head east.

It separates "global crude flows into smaller, macro-regional trading realms", JBC Energy analysts said in a note.

Several popular grades in Asia, such as Oman, Russian ESPO and Sokol crude, traded at the highest premiums in 11 months against Dubai quotes while Qatar set its August term premium for al-Shaheen crude at a 17-month high.

In addition to stronger Brent prices, Atlantic Basin grades have also become more costly for Asian refiners as spot premiums for these crude have risen, traders said.

"The uptick in demand is whetting refiners' appetite ahead of the summer season, compelling refiners to soak up barrels from West Africa, the Mediterranean and the Black Sea," JBC Energy said.

Spot premiums for gasoline-rich west African flagship grades like Bonny Light or Qua Iboe have increased by almost $1.50 per barrel over the past four weeks, it added.