WeeklyUS stocks fall gives crude a shot in the armSlip in prices early in week, amid expectations of supply increase by key producers, reversed after bigger-than-forecast drop in storage levels, plus predictions for strengthening demandSee-saw effect: any price drop resulting from an increase in supply by the world's main producers is likely to be limited by the effects of sanctions on Iran and spiralling production problems in Venezuela (pictured)Nassir ShirkhaniLondon