Crude oil prices fell on Monday after U.S. unions called a refinery strike and traders cashed in on strong price gains last week when the market soared on a sharp drop in U.S. drilling. Brent crude oil futures were trading at $51.60 a barrel at 0440 GMT, down $1.39, while U.S. WTI futures were at $46.96, down $1.28 a barrel. This supports our view that oil prices will recover this year and average $60 per barrel for Brent,” Nomura said.