The convergence of the two front-month crude benchmarks comes as increased pipeline capacity has drained the glut of oil at the WTI delivery point of Cushing, Okla., to the Gulf Coast, where refinery demand has been high.
The easing of the Cushing glut has not led to lower prices at the Gulf Coast as refineries there are eager to cash in on robust margins and exports.
The price rally also has been driven by concerns that the market is flipping from glut to drought, fueling a sharper run in prompt contracts to create a backwardated market, with near-term prices higher than those further in the future.
"The extraordinarily strong backwardation is strengthening and bringing everyone into the WTI," said Olivier Jakob, an analyst at Petromatrix in Zug, Switzerland.
Brent could garner support from a stronger demand growth outlook and supply risks in the Middle East and Sudan, according to Carsten Fritsch, analyst at Commerzbank.
Hedge funds amassed record bets on rising U.S. crude oil prices in the week to July 16, trade data by the U.S. Commodity Futures Trading Commission showed.
A pledge on the weekend by the Group of 20 nations, which account for 90 percent of the world economy, to put growth before austerity has fueled hopes of a recovery in the consumption of commodities.
The market watched also closely as Japanese Prime minister Shinzo Abe won a decisive victory in upper house elections, which was seen as a boost for his radical economic stimulus policies.