Plunging crude oil prices mean lower costs and greater availability for most of the materials and services used by oil producers. But one vital commodity remains in short supply: engineering talent. Cambridge Energy Research Associates has predicted that half of the globe's petroleum engineers will retire by 2015. That is of particular concern in the Gulf, which holds about 60 per cent of global oil reserves. In Abu Dhabi, as in the region's other top oil-producing states, crude exports account for a good part of the national wealth and is the source much of the country's foreign currency reserves.