Oil rigs are scarce commodities these days; so scarce that it can be easier to buy a company that owns them than to buy the rigs themselves. That is one of the main motives behind China Offshore Services’ $2.5bn acquisition of Awilco Offshore.

There has been a high level of sensitivity over Chinese companies’ acquisitions of natural resources, most notoriously in the attempt by China National Offshore Oil Company, COSL’s parent, to buy Unocal of the US in 2005.