- Hyedua-1 well, Deepwater Tano

LONDON, Aug. 22 /PRNewswire/ -- Tullow Oil plc (Tullow) announces that the Hyedua-1 well, drilled on the Deepwater Tano license offshore the Republic of Ghana, has discovered a significant light oil accumulation based on the results of drilling, wireline logs and samples of reservoir fluid. Initial data from the well indicates that the Hyedua-1 and Mahogany-1 wells are likely to represent a single continuous trap extending across the West Cape Three Points and Deepwater Tano blocks. Tullow operates the Deepwater Tano license (49.95%) and also holds an interest in the West Cape Three Points license (22.9%).

Hyedua-1 is being drilled as the initial exploration well on the Deepwater Tano license. The well is targeting the equivalent Santonian turbidite sandstones encountered in the Mahogany-1 discovery well located some 5.3km to the northeast of Hyedua-1 on the adjacent West Cape Three Points license. It is being drilled by the "Belford Dolphin" deepwater drillship in water depths of 1,530m and has been drilled to a total depth of 4,002m.

The well has encountered a gross reservoir interval of 202m, containing 108m of high quality stacked reservoir sandstones, and net hydrocarbon-bearing pay of 41m. In addition, the results of logging and pressure testing indicate the strong likelihood that the reservoir sands are in communication with the Mahogany discovery, indicating combined hydrocarbon columns in excess of 361m within a continuous accumulation which extends across the Deepwater Tano and West Cape Three Points licenses. The well will now be sidetracked, prior to casing, to acquire core data over the reservoir interval and suspended for potential use as a development well.

Planning is already under way to rapidly appraise the accumulation. Suitable vessels have been identified to carry out a 910 sq km high-resolution 3D seismic survey, covering the combined feature on both the Deepwater Tano and West Cape Three Points blocks, and a program of up to three additional appraisal wells in late 2007.

Tullow's partners in the Deepwater Tano license are Kosmos Energy and a subsidiary of Anadarko Petroleum Corporation, (18% each), Sabre Oil & Gas (4.05%) and the Ghana National Petroleum Corporation (GNPC) (10% carried interest).

Commenting today, Aidan Heavey, Chief Executive of Tullow said: "The discovery of oil in Hyedua-1, and the confirmation of its communication with the recent Mahogany discovery, represents a major step forward for the Republic of Ghana and for Tullow and its partners. It significantly enhances our understanding of the resource, enables us to focus and accelerate our appraisal program, and is highly encouraging for our plans to establish commercial production in Ghana."

Tullow is a leading independent oil & gas, exploration and production group, quoted on the London and Irish Stock Exchanges (symbol: TLW) and is a constituent of the FTSE 250 Index. The Group has interests in over 120 exploration and production licenses across 23 countries and focuses on four core areas: Europe, Africa, South Asia and South America.

Tullow's European interests are primarily focused on gas in the UK Southern North Sea where it has significant interests in the Caister-Murdoch System and the Thames-Hewett areas and operates over 70% of its production.

In Africa, Tullow has exploration and production in Gabon, Cote d'Ivoire, Congo (Brazzaville), Mauritania and Equatorial Guinea and a large gas field development and appraisal program in Namibia. Tullow also has exploration program in Mauritania, Senegal, Cameroon, Uganda, Congo (DRC), Tanzania, Madagascar, Angola and Ghana. In Ghana, in addition to the two deepwater licenses, Tullow also holds a 31.5% interest, as Operator, in another separate license, Shallow Water Tano, which is not the subject of this release but where a well is due to be spudded within the next few weeks.

In South Asia, Tullow has exploration and production in Pakistan and Bangladesh and high impact exploration activities in India.

In South America Tullow has high impact exploration interests in Trinidad and Tobago, French Guiana, Suriname and the Falkland Islands. For further information please refer to our website at http://www.tullowoil.com

Contact: Aidan Heavey Tom Hickey Chris Perry Tullow Oil plc

+ 44-20-8996-1000

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Brian J. Rafferty

Taylor Rafferty

212-889-4350