Geologists believe that the petroliferous structures discovered in the deep blocks extend westwards into contiguous ultra-deep blocks.

ECONOMIST: Angolan oil: Drilling down | The

It was such successes that fuelled the frenzied bidding last year, when the first three ultra-deep blocks (numbers 31, 32 and 33) became available.

ECONOMIST: Angolan oil: Drilling down | The

China's capital may be racing towards the future at breakneck speed but sneak behind one of the city's glittering, ultra-modern tower blocks and you find a slice of old Beijing that seems to have been lost in time.

BBC: Old Beijing at its timeless best