Significant Oil Discovery

Tullow Oil PLC
18 June 2007

News release




Tullow Oil plc - Significant oil discovery offshore Ghana


18 June 2007 - Tullow Oil plc (Tullow) announces that the high impact Mahogany-1
exploration well drilled on the West Cape Three Points licence 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.



The well, which is drilling in water depths of 1,320m, has been drilled to a
depth of 3,683m and has to date, encountered a gross hydrocarbon column of 270m
with 95m of net stacked pay.  It is planned to drill to a total depth of
approximately 4,200m to test further prospective horizons. Upon reaching the
target depth, the well will be suspended pending further evaluation and
additional appraisal drilling will be required.  The Mahogany-1 well will be
tested at a later date as part of the appraisal programme.



The Mahogany discovery, a Santonian turbidite stratigraphic trap, opens a new
play fairway in the Tano Basin. The structure straddles both the West Cape Three
Points and Deepwater Tano licences in which Tullow has interests of 22.9% and
49.95% respectively. Tullow is also the operator of the Deepwater Tano licence.



The Mahogany-1 well was drilled using the 'Belford Dolphin' - a dynamically
positioned fifth-generation deepwater drillship.  This is the first exploration
well to be drilled under the West Cape Three Points seven-year exploration
agreement and follows a 1,076 sq km 3D seismic survey on the block in 2005.


Commenting today, Aidan Heavey, Chief Executive of Tullow said:

'The discovery of oil in the Mahogany well represents a major event for the
Republic of Ghana and for Tullow. Based on evidence to date, ultimate reserves
are likely to be materially in excess of previous estimates, with some
high-potential zones still to be drilled. We look forward to working with our
partners to realise the full potential of Mahogany and our additional prospects
in the region'



Conference Call
Aidan Heavey (CEO) will host a conference call at 9.30 a.m. today.  Please
dial-in 10 minutes before the start time.  A replay facility will be available
from 1pm.  The details for accessing the live call and the replay are as
follows:

                        Live Event                                      Replay Facility available from 1 pm

      UK Participants                020 7806 1950                 UK Participants                020 7365 1827
     Irish Participants               01 655 8885                Irish Participants                01 659 8321
     Other Participants             [phone]             Other Participants             [phone]
                                                                     Access Code                    2405197#



For further information contact:

Tullow Oil plc                     Citigate Dewe Rogerson              Murray Consultants
([phone])                 ([phone])                  ([phone])
Aidan Heavey                       Martin Jackson                      Joe Murray
Tom Hickey
Chris Perry





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 250 Index. The Group has interests in over 120
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.

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 programme in Namibia. Tullow also has exploration
programmes in Mauritania, Senegal, Cameroon, Uganda, Congo (DRC), Tanzania,
Madagascar, Angola and Ghana.

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 www.tullowoil.com


                                      ENDS


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