Goldman Sachs stirred energy investors last month when its head of commodity research warned of rising risks of oil prices falling as low as $20 per barrel, in a message that was reiterated on Tuesday.
"The risk of $20 is driven by what we call a breach in storage capacity, meaning that you have supply above demand, you fill every storage tank on planet earth and then you have nowhere to put it," Jeff Currie, head of commodity research at Goldman told CNBC from the annual Oil & Money conference in London.
"(Then) supply has to come down in line with demand. The only way you get that correction is prices crash down to cash costs, which for a U.S. producer, is somewhere around $20 a barrel."