Exploration Update

RNS Number : 7263A

Tullow Oil PLC

06 August 2008

News release

Uganda Drilling Update

6 August 2008 - Tullow Oil Plc ('Tullow') is pleased to provide the following update on Exploration and appraisal drilling obligations in Uganda.

Kasamene-1 Exploration well, Block 2

The Kasamene-1 exploration well, drilled in the Butiaba region of Uganda Block 2, has encountered over 31 metres of net oil pay and at least 6 metres of net gas pay.

The well was drilled some 1.5km from the crest of the structure to a total depth of 957 metres and has been successfully logged. Downhole pressure testing and sampling has confirmed the presence of dry gas and moveable 30-33 degree API oil. Reservoir quality for both zones is excellent. The most likely gas column is over 35 metres and the most likely oil column is over 75 metres. Further potential exists up-dip and an appraisal well will be required to test the vertical extent of the oil legs and gas cap. The well is currently being sidetracked and core will be taken throughout the reservoir section for analysis.

Kasamene-1 was drilled 15km to the north-west of the Ngege-1 discovery and is the second successful test of the Victoria Nile delta play fairway within the Lake Albert Rift Basin. The well results have confirmed the presence of excellent quality thick reservoir and seal units within the centre of the basin, and de-risks several adjacent prospects in Blocks 1 and 2 that will be drilled as part of the current 9 well Butiaba drilling campaign.

On completion of operations at Kasamene-1, the rig will move 10 kilometres to the East and drill the Kigogole-1 prospect starting in mid August.

Kingfisher-2 well, Block 3A

This deviated appraisal well has been drilled to a total depth of 3,906 metres, (3,197 metres true

vertical depth). Three zones will be production tested, which, based on a preliminary evaluation of

wireline log data, have an estimated net thickness of 37 metres over a gross interval of

approximately 100 metres. These three zones appear equivalent to the Upper Miocene discoveries

in the Kingfisher-1 well.

In the targeted deeper section the well penetrated the anticipated basal sands comprising

approximately 30 metres of reservoir overlain by a good potential shale top-seal. Although no

hydrocarbons were present in the basal sands at this location, it is considered that these could

still be an important reservoir target for other prospects within Block 3A, that will be evaluated as

part of the planned Lake Albert offshore drilling programme in 2009.

Testing of the Kingfisher well is expected to be complete before the end of this month.

Aidan Heavey, Chief Executive of Tullow commented:

' Kasamene-1 is the most important result to date in Tullow's Butiaba drilling campaign. In addition to maintaining our 100% exploration success record in Uganda, this result indicates the potential for further significant discoveries from the Victoria Nile delta play, and is likely to represent an important element of longer term commerciality planning. While the deep exploration objective in the Kingfisher-2 well at this location did not find additional hydrocarbons, this well has proved up a significant discovery. These results increase our confidence of quickly achieving the reserve volumes required for a major development'

For further information contact:

Tullow Oil plc
(+44 20 8996 1000)

Aidan Heavey

Tom Hickey

Angus Mc Coss

Citigate Dewe Rogerson
(+44 20 7638 9571)
George Cazenove

Murray Consultants
(+353 1 498 0300)
Joe Murray

Joe Heron

Notes to Editors

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 100 Index. The Group has interests in over 100 exploration and production licences 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. The company also has interests offshore the Netherlands and Portugal.

In Africa, Tullow has exploration and production in Gabon, Côte d'Ivoire, Mauritania and Equatorial Guinea and two large appraisal and development programmes in Ghana and Uganda. Tullow also has exploration interests in Mauritania, Senegal, Congo (DRC), Tanzania, Madagascar, Namibia and Angola.