After two years pursuing a Saudi-led strategy to pump without limits, pummeling industry earnings, OPEC has unexpectedly come to the aid of the oil majors. Last month, it surprised the market by deciding to cut production and put a floor under volatile crude prices.

The question now is how soon they will resume drilling. Prices are near levels where many majors have said they can start investing again after billions of dollars of spending cuts and thousands of job losses sent discoveries to the lowest level in 70 years. In U.S. shale fields, explorers are already adding rigs, boosting oilfield work to the highest since February.

“After all the hell we’ve had, there should be a pick-up now,” said Danilo Onorino, a portfolio manager at Dogma Capital SA, which owns oil companies’ bonds. “The industry has been damaged in the past two years and things need to start improving.”

Saudi Arabia’s Energy Minister Khalid Al Falih has said getting explorers to start drilling again is one of the reasons behind the OPEC deal. He’ll be joined at the Oil and Money conference by company bosses that include BP Plc’s Bob Dudley, Rex Tillerson of Exxon Mobil Corp. and Chevron Corp.’s John Watson.

“He needs to convince everyone to start investing again else there is a big supply crisis coming,” Onorino said. “If prices remain at these levels for about six months, the industry’s spending should start moving higher.”

Oil’s slump has forced Saudi Arabia, OPEC’s de facto leader, to cut fuel subsidies and even borrow money to finance its budget. Though the kingdom needs higher prices, it will be wary of a jump that could spur development of alternative energies and limit demand for its vast resources of crude.

While Brent has climbed as high as $53.73/bbl since oil producers announced a preliminary deal in Algiers on Sept. 28, prices remain at less than half their mid-2014 level. Still, if crude holds above $50, it may be enough to encourage spending by an industry made leaner by two years of cost cuts.

Total SA, France’s largest oil company, is “almost happy” to see crude at $50 to $55, CEO Patrick Pouyanne said in Istanbul on Oct. 11. The CEO welcomed OPEC’s decision to limit supply, saying that investment cuts in the industry had blocked new projects, threatening to cause an oil shortage by 2020.