Oil prices ended Wednesday's trading session higher, but data showing rising U.S. stockpiles and production capped gains.
Supplier cutbacks, steady demand growth, geopolitical tensions and a favorable structure in the futures market have attracted record investment in oil this year.
A rise in U.S. government borrowing costs to their highest since 2013 this week has tempered some investor appetite for risk, but analysts said Brent crude futures, the global benchmark, may yet rise toward new 2018 peaks above $75 a barrel.
U.S. West Texas Intermediate (WTI) futures finished Wednesday's session up 35 cents at $68.05 a barrel.
Brent crude oil futures settled 14 cents higher at $74 a barrel. The contract hit a high going back to November 2014 at $75.47 in the previous session.