Weak refining margins dinged first-quarter results for Exxon Mobil and Chevron today.
However Chevron's oil production gains outshone its larger rival, which has struggled to turn operations around after recent missteps.
Refining and chemical operations hurt two of the world's largest integrated energy companies for the second consecutive quarter, highlighting concerns about the impact of volatile oil prices on their businesses.
US producers are accelerating shale drilling mostly in the Permian Basin of west Texas and New Mexico, the largest US oilfield.
This has lifted the nation's output this year to more than 10 million barrels per day - a new record.
But the higher output has not translated into stronger refining results for the biggest oil companies.
Chevron and Exxon are struggling with spotty demand in key markets outside the US for refined products.
Oil prices rose in the first quarter over a year earlier but bounced up and down during the period, zapping profit for the downstream divisions. Rising oil prices typically harm refiners by squeezing their margins on products.
Strength in the Chevron division that pumps oil and gas helped overcome the refining weakness and beat Wall Street profit expectations for the quarter.
Exxon, though, has struggled in recent quarters in its upstream division, and its results badly lagged expectations.
In Exxon's downstream refining unit, profit fell 12%, and earnings in its chemical unit were down 14%.
Profit in Chevron's refining and chemical operations dropped 21% to $728m.
Refining margins in Europe fell more than 14% in the quarter and were on track for a 38% drop in the second period, the biggest quarterly decline since the fourth quarter of 2015.
Both companies have been trying different ways to bolster refining operations.
Reuters reported earlier this month that they have asked US regulators for exemptions to US biofuels rules that are typically only given to small companies in financial distress.
While Exxon's overall results missed estimates, Chevron easily beat targets set by analysts, largely due to the fruits of its years-long push to bolster oil and gas production operations, especially in liquefied natural gas (LNG) and US shale.
It was a market turnaround for Chevron, which last quarter posted dismal results alongside Exxon.
Exxon has struggled in the past 16 months to unwind some of the biggest bets taken by its former chief executive officer, Rex Tillerson, who left to become US secretary of state in early 2017 before being fired by President Donald Trump last month.
Exxon shares are off about 6.6% in the last two years while Chevron has soared 24.5%.
