“Looking toward 2012, the stage is set for a return to a structural bull market in oil,” the analysts said in the report dated today. The 2012 forecast is based on “the better prospects for continued robust world economic growth.”

A 2.4 million-barrel-a-day increase in global oil demand in 2010 will be sustainable at more than 2 million barrels a day in 2011 and 2012 and require OPEC to tap into its spare capacity, the Goldman analysts said.

The Organization of Petroleum Exporting Countries had spare capacity of 5.64 million barrels a day in November, according to Bloomberg estimates. That compares with 2 million barrels a day in July 2008, when New York-traded oil futures reached a record $147.27 a barrel.

Oil for January delivery gained $2.29, or 2.7 percent, to $86.40 a barrel at 12:35 p.m. on the New York Mercantile Exchange. Crude has averaged $78.72 a barrel so far this year.