UPDATE 1-Ecopetrol's Cartagena refinery to restart around May 2015

CARTAGENA, Colombia, April 3 (Reuters) - Colombia's state-run oil company Ecopetrol will restart its 80,000 barrel per day (bpd) refinery in Cartagena in the first half of 2015 after expansion works and most likely in May, a senior company official said on Thursday.