VIENNA — OPEC oil ministers have effectively scrapped their official output ceiling and agreed to keep producing above that level. A statement at the end of their meeting Friday did not mention any decision on how much the 12-nation group should pump. But officials told reporters that there was an agreement to continue producing at present numbers. The official ceiling remains 30 million barrels a day. But for more than a year there has been overproduction ranging from just over 1 million barrels a day to nearly twice that much. OPEC is unhappy with crude prices hovering at around $40 a barrel. But only a few members appeared ready to cut output in an attempt to drive up both supply and prices.