Oil prices climbed on Friday as markets tightened amid output cuts by producer club OPEC, but surging U.S. supply and concerns of global economic slowdown kept a lid on further gains. International Brent crude futures were at $66.85 per barrel at 0750 GMT, up 54 cents, or 0.81 percent, from their last settlement. U.S. West Texas Intermediate (WTI) crude oil futures were at $57.66 per barrel, up 44 cents, or 0.77 percent. Traders said oil markets were currently tightening. In Venezuela, oil exports have plunged by 40 percent to around 920,000 barrels per day (bpd) since the U.S. government slapped sanctions against its petroleum industry on Jan. 28. This drop comes as the Organization of the Petroleum Exporting Countries (OPEC), of which Venezuela is a founding member, has […]