Summer road trips and a pullback in crude prices have pumped up refineries’ profits, offering brighter prospects for one part of the global oil complex despite rising worries about Covid-19. Oil prices have grown choppy in recent weeks since China, the world’s biggest commodities consumer, imposed restrictions to contain the Delta coronavirus variant. A decision by the Organization of the Petroleum Exporting Countries, Russia and the cartel’s other partners to pump more oil is also weighing on crude markets.

Prices for West Texas Intermediate, the main grade of U.S. crude, are down more than 10% from their 2021 high, trading at $65.46 a barrel. Crude-oil futures prices in 2021Source: FactSetAs of Aug. 18

Jan. 2021Feb.MarchAprilMayJuneJulyAug.45505560657075$80a barrelBrentWest TexasIntermediate

The retreat is weighing on shares of energy companies including Exxon Mobil Corp. , but is a potential boon for refiners such as Marathon Petroleum Corp. Refiners stand to gain when gasoline and other products they produce fetch higher prices than the crude they purchase.

Refiners play a key role in energy markets, processing crude oil into fuels for transportation and heating, as well as petrochemical ingredients and products such as asphalt. When profits at refiners rise, the companies typically crank up production, lifting demand for crude.

One gauge of U.S. refiners’ profit margins—the gap between the price of gasoline and crude futures—stood at $25.58 a barrel Wednesday. That was close to the highest level for this indicator, known as the crack spread, on FactSet data dating back to 2016.