U.S. crude oil futures extended a rally Friday afternoon to above $91 amid supply concerns raised by Exxon Mobil's dispute with Venezuela.
Analysts also cited support from a heating oil futures rally due to colder weather ahead in the U.S. Northeast, output snags in Nigeria and a decline in North Sea Brent crude production.
On the New York Mercantile Exchange 1 p.m. EST, US light, sweet crude was up $3.45, or 3.92 percent, at $91.56 a barrel, trading from $88 to $91.94, highest since the $92.12 reached on Feb. 1. Thursday's low was $86.24 and support has held at around $86.10.
"The Venezuelan story is helping push prices up," said Nauman Barakat, senior vice president at Macquarie Futures USA. "The fear is that (President Hugo) Chavez might do something unexpected, which could spike oil prices yet again."
Barakat said he was hearing that funds were in the market covering shorts on concerns about the geopolitical implications of Exxon Mobil's dispute with Venezuela.
In London, March Brent crude surged $3.42, or 3.86 percent, to $91.93 a barrel, trading from $88.78 to $92.32.
NYMEX March heating oil gained 10 cents, or 4.07 percent, to $2.5585 a gallon, trading from $2.4614 to $2.5493.
March RBOB was up 8.62 cents or 3.8 percent to $2.3540 a gallon, trading from $2.2645 to $2.3630.