Royal Dutch Shell CEO Peter Voser gestures while addressing 150 international industry leaders at the Spruce Meadows Round Table Forum in Calgary, Alberta, September 11, 2009. Another round of significant oil price increases could come within four to five years because oil companies slashed investments to cope with last year's plunge in oil prices, Voser said on Friday. REUTERS/Jack Cusano (CANADA BUSINESS ENERGY IMAGES OF THE DAY)