Wessex Exploration PLC announced that GM-ES-4 (Cebus), the third well of the current four well exploration programme in the Guyane Maritime Permit (French Guiana) has been spudded by Shell as Operator on 3 May 2013. Wessex owns a net 1.25% interest in the offshore exploration licence 'Guyane Maritime' through its holding of 50% of Northpet Investment Limited. Wessex is in partnership with Shell (Operator, holding 45%), Tullow (27.5%), Total (25%) and Northern Petroleum Plc (also holding 1.25% through owning the remaining 50% interest in Northpet Investment Limited).

Wessex Exploration PLC announced the conclusion of drilling activities on GM-ES-3 (Priodontes) in French Guiana. At 6,318 metres depth, drilling was terminated. The well had reached sufficient depth to evaluate the deeper potential reservoir, encountering an estimated 65 metres of target formation. With no indications of hydrocarbons the well is now being plugged and abandoned. The Stena ICEMax will now move on to the GM-ES-4 (Cebus) exploratory well designed to test a different fan system to the previous three wells drilled by the Joint Venture. It is anticipated that the new well will be spudded in early May 2013. GM-ES-4 is the third well of a four well exploration drilling campaign that commenced in 2012 to follow up the oil discovery at GM-ES-1 in 2011.

Wessex Exploration PLC announced the initial results of current drilling operations on the Guyane Maritime permit (French Guiana) and the decision to extend drilling operations to a deeper target. The GM-ES-3 exploration well is the second well of a four well exploration drilling campaign that commenced in 2012 to follow up the oil discovery at GM-ES-1 in 2011. The GM-ES-2 well had exploration objectives in the major Cingulata fan system within which the original oil discovery was made in two ages of formation. GM-ES-3 has been planned to deliver exploration information in the subsidiary Priodontes fan system to the north west of the Zaedyus oil discovery. The GM-ES-3 well intersected a 50 metres gross section of oil stained sands in the lower part of the Bradypus fan which was not a target formation at this location although it is also within the main Cingulata fan system. A 325 metres gross interval of sands was encountered in the targeted Priodontes fan, but these were logged with no significant hydrocarbon shows.