Oil extended losses from the lowest level in more than 5 1/2 years as Goldman Sachs Group Inc. reduced its price forecasts and Venezuela called on OPEC producers to work together to spur a recovery. Futures slid as much as 3.1 percent in London after a seventh weekly drop. Crude has to “stay lower for longer” if investment in shale is to be curtailed to re-balance the global market, according to Goldman analysts. Prices need to return to $100 a barrel for economic equilibrium, Venezuelan President Nicolas Maduro said in Iran during a tour of Middle Eastern members of the Organization of Petroleum Exporting Countries. Oil slumped almost 50 percent last year, the most since the 2008 financial crisis, amid a supply glut estimated by Qatar at 2 million barrels a day. OPEC is battling a U.S. shale boom by resisting production cuts, signaling it’s prepared to let prices […]