Lenders including JPMorgan Chase & Co., Wells Fargo & Co. and Bank of America Corp. are setting aside more money to cover potential loan losses after crude prices fell 61 percent in less than two years.

“The oil price is growing. I think everyone is expecting the successful outcome of our work,” Mr Sechin said. “We will need higher price levels than $45 or even $50 a barrel.”

"Now we're seeing reductions in spending on shorter cycle projects, in other words immediate drilling activity," Watson said. "Rig rates in the US are down almost 80%, we're seeing decline in rig rates around the world and we're starting to see the supply response that everyone has expected. So we're seeing the markets come back into better balance [but] it may take more time."

The squeeze puts further pressure on the shale industry to sell assets, cut jobs and drilling and shrink capital spending. It also raises the risk that more companies will tip into bankruptcy.

The world's top crude oil exporter asked banks for a loan worth between $6 billion and $8 billion that would run for five years, sources told Reuters last month, as the kingdom seeks to plug a record budget deficit caused by low oil prices.

Chevron Corp. and Royal Dutch Shell Plc had their ratings reduced by one level, while Total SA’s was cut two steps, according to statements by the New York-based rating company on Friday. Chevron will generate negative cash flow amid rising debt for at least the next two years, while Shell will have elevated leverage following its acquisition of BG Group Plc, Moody’s said. Prices are expected to stay low through this year and next and continue to pressure Total’s operating cash flows and credit metrics, Moody’s said.

"The level of $45-50 (per barrel) is acceptable from the point of view of market balance: if prices go higher shale oil production could start to recover."

Oil-producing countries can come to an agreement capping crude production at January levels even if Iran doesn’t join the move to help shore up prices.

Oil at $35 a barrel is neither too high nor too low but just right to make shares of U.S. explorers worth buying, according to Goldman Sachs Group Inc.

The cumulative effect suggests that for U.S. growth over the next three years, there's no difference between oil at $30 or $70 per barrel. How the trade balance responds to swings in crude will dictate which path is more desirable.