If it is a "W" class ticket, you will be able to earn miles, but you will not be able to use miles to do an upgrade:
http://www.singaporeair.com/saa/en_U...edeemMiles.jsp
Only Economy Class tickets purchased on Singapore Airlines in S, Y, B or E booking classes or Y, B, E booking classes on SilkAir, are eligible for redemption of upgrades from Economy to Business.