sentences:  As a result of restructuring and several transactions the field became held by BP (59.5%), BG (24.15%), Centrica (8.95%), and Murphy Oil (7.4%).In December 2009, BP and BG agreed an assets swap by which BP took over BG's interest in the field.In September 2007, three crew members of the emergency response and rescue vessel "Viking Islay", operated by Vroon Offshore Services, were killed during a support operation on the Amethyst gasfield.