Shares in San Leon and Genel Energy took a hit on Thursday after the groups reported that the M-1 well on the Sidi Moussa permit offshore Morocco was to be plugged and abandoned.The well failed to produce product oil at sustainable rates, which it said was potentially the result of reservoir damage suffered during drilling and well control operations."Further evaluation of the well results and other subsurface information is required before any definitive conclusions can be drawn," Genel said.The well is 60% operated by Genel, while San Leon holds a 10% stake.San Leon executive chairman, Oisin Fanning, said: "Analysis of the oil recovered, and the suite of data from drilling, logging and testing, provides a good platform for evaluating the potential of the Sidi Moussa licence and its various prospects. This evaluation work will begin immediately."Shares in San Leon slumped almost 20% after the group, while Genel was around 3.5% lower.