Oil extended gains in its longest rally since the end of December on increasing confidence that OPEC’s supply curbs will outweigh a gain in U.S. crude stockpiles. Futures in London added as much as 0.6 percent, after gaining 1.8 percent over the past three sessions. The Organization of Petroleum Exporting Countries is confident members will continue to cut production and reduce global stockpiles, Secretary-General Mohammad Barkindo said. While U.S. inventories probably expanded last week, they are seen shrinking once some of the nation’s refineries resume operations next month after maintenance. A surge in U.S. crude stockpiles to the highest level in more than three decades at a time when OPEC and 11 other nations are trimming supply to ease a global glut has kept oil futures in a tight range above $50 a barrel this year. But with the exporters group implementing about 90 percent of the pledged cuts […]