Royal Dutch Shell chief executive Ben van Beurden has told the BBC a recovery in the price of oil is hard to foresee.
"It is a very, very volatile business in terms of supply and demand. The oil price responds to very small mismatches between supply and demand," he told BBC Radio 4's Today programme.
The price of oil has roughly halved in the past year, to around $50 (£32) per barrel.
Goldman Sachs predicted earlier this month it could fall as low as $20.
When asked where oil prices may go next, he told the BBC: "The honest answer to that is I don't know."