Sharp reductions in investments and low oil prices could curb future supplies by almost eight million barrels a day within the next five years, according to a study scheduled for release Friday, the latest warning that the world could face a new energy shock when the economy picks up.

The report by Cambridge Energy Research Associates, an oil consulting firm, said that the potential drop in production capacity is a “powerful and long-lasting aftershock following the oil price collapse.”

The global slowdown has forced oil companies to slash their investments, postpone or cancel expansion plans, or delay drilling in many corners of the world. While some of the biggest companies, like Exxon Mobil and Royal Dutch Shell, say they will keep their investments unchanged this year, many other producers are curbing investments because of the crisis.

The report says about 7.6 million barrels a day of future supplies are “at risk” of being deferred or canceled, like heavy oil or deepwater projects, and which could bring total supplies to 101.4 million barrels a day by 2014. Last year, the group projected that capacity would rise to 109 million barrels a day by then.