Oil prices slumped by more than 6 percent as the Brexit vote raised fears of a broader economic slowdown that could reduce demand for oil.
Shell purchased four August Dubai partials from Reliance, Chinaoil and SK Energy at $45.35-$45.40 a barrel, traders said. The trades narrowed cash Dubai's discount to swaps by 10 cents to 13 cents a barrel.
DME Oman's premium to Dubai swaps rose by close to 20 cents on Friday.
Outside the window, spot trade slowed as most refiners have completed their purchases for August-loading barrels. Thailand's PTT will award a tender soon to buy crude on behalf of IRPC. PTT was in talks with sellers to buy ESPO and Upper Zakum, a trader said.