oil could fall to around $83 per barrel in today's money by 2035, PwC estimated, or $50 less than the EIA's 2035 real-terms forecast price of $133.
Brent crude oil is currently trading around $119 per barrel.
Lower oil prices will feed into stronger GDP growth, adding $1.7-$2.7 trillion per year, or $230-$370 per person, PwC said.
The level of support will vary greatly, however, from country to country, it said.
"Large net oil importers such as India and Japan may see their GDP boosted by around 4 to7 percent by 2035 in our alternative scenarios, while the U.S., China, Germany and the UK might gain by around 2 to 5 percent of GDP," Hawksworth said.