Tullow Oil plc (Tullow) announces that the Zaedyus exploration well (GM-ES-1), offshore French Guiana, has made an oil discovery having encountered 72 metres of net oil pay in two turbidite fans. Results of drilling, wireline logs and samples of reservoir fluids show that the well has encountered good quality reservoir sands on prognosis.

The objective of the Zaedyus well was to test whether the Jubilee-play, successfully established in West Africa, was mirrored on the other side of the Atlantic. This discovery therefore opens a new hydrocarbon basin within which several neighbouring prospects have been mapped. This result also reduces the exploration risk associated with Tullow's prospect inventory offshore French Guiana, Suriname and Guyana. An appraisal programme and extensive follow-up exploration activities will now be considered.

The Zaedyus well is being drilled in the Guyane Maritime licence using the ENSCO 8503 deepwater semi submersible. The well was drilled in water depths of 2,048 metres and has been drilled to a depth of 5,711 metres. Drilling operations will now continue and the well will be deepened to over 6,000 metres to calibrate the deeper geology. The well will then likely be sidetracked to enable cores to be obtained over the reservoir sections.

Tullow (27.5%) operates the Guyane Maritime license and is partnered by Shell (45%), Total (25%) and Northpet (2.5%), a company owned 50% by Northern Petroleum plc and 50% by Wessex Exploration plc.