Does OPEC have enough spare capacity?

As world oil demand continues to rise strongly, OPEC is raising its own output accordingly. At present, markets seem to be adequately supplied and crude oil stocks show signs of increasing in the US and other major markets. Most OPEC countries, however, are now producing close to their physical limits and there are increasing worries that if demand goes on growing at its present rate there will be scarcely any spare output capacity available outside Saudi Arabia.