Shell ascends on Q1 profit beat, $3.5 bln buyback

** Shares in Shell SHEL up 1.3% at 2,856p

** The oil gaint posts adj profit of $7.7 bln for Q1, beating market view, announces $3.5 bln share repurchase

** Better-than-expected results on back of strong oil trading, higher refining margin

** Co keeps dividend unchanged from last qtr

** Up to last close, stock had risen 9.6% so far this year