OPEC on Thursday cut its estimate for world oil demand over the next two decades, predicting that high prices would compel consumer countries to be more efficient in their use of the precious commodity.In its annual World Oil Outlook, released on Thursday, the Organization of Petroleum Exporting Countries, forecast that world oil demand would amount to 113.3 million barrels per day (bpd) in 2030. That is lower than the cartel's previous forecast of 117.6 million bpd published a year ago. For the current year, the cartel is forecasting total world oil demand of around 86.9 million bpd. Since last year, oil prices have more than doubled, OPEC calculated, with the cartel's own reference basket price soaring from $71 in mid-2007 to more than $130 in June 2008. The lower forecast for world oil demand "reflects greater efficiency improvements due in part to the higher oil price assumption," it wrote. Developing countries would account for most of the anticipated rise in demand. The oil cartel insisted that there was no danger of the world's oil reservoirs running dry.