(ShareCast News) - Shares in Circle Oil fell on Wednesday after the company said it has plugged and abandoned the Ksiri South exploration well on Sebour permit onshore Morocco.Chief executive officer Mitch Flegg said: "The drilling conditions at KSS-A proved challenging, and as a result it was decided to plug and abandon the well in order to allow time for a new well design to be engineered."This was the most cost-effective approach and it will allow drilling of the KSR-A well to commence ahead of schedule. Although we are disappointed to have not reached the prognosed TD of KSS-A, we have minimised any cost implications by quickly moving on to the next well in the campaign."Circle said the well, which was targeting two objectives in the Miocene Gaddari sands, encountered unexpected lithology above the primary objectives. The technical data from the well is being assessed in line with available seismic with a view to assessing further drilling in this area at a later date, the company said.The rig will now be mobilised to drill the Ksiri West (KSR-A) exploration well in the Sebou permit in the Rharb Basin.At 0917 BST, Circle Oil shares were down 7% at 5.00p.