Tullow Oil proposes to acquire additional equity in the Thames gas fields from Eni

17th July 2003

Tullow Oil plc (“Tullow”), the independent international oil and gas exploration and production company, announces that its wholly-owned subsidiary, Tullow Oil UK Limited (“TOUK”), has entered into an agreement with Eni UK Limited (“Eni”), a wholly-owned affiliate of Eni S.p.A., to acquire their 23.33% equity in the Thames gas fields and the associated licence interest, P037 (Block 49/28). Tullow has an existing 43.33% interest in Thames, purchased from BP/ARCO in 2001.

The total consideration for the transaction is £5.2 million, with an effective date of 1st January 2002. The net consideration payable by Tullow on completion will be adjusted to reflect revenues and costs accruing to the interest since the effective date. The net remaining reserves attributed to the acquired interest at the effective date are estimated at 10 bcf of sales gas. Gas associated with this interest is sold on long-term contract to British Gas Trading as part of the same common stream as for Tullow’s existing interest.

Completion of the transaction is anticipated to occur in late 2003 subject to the necessary governmental and co-venturer approvals.

John Lander, TOUK’s Managing Director, stated:

“Thames is an important hub for existing gas fields and possible future developments, such as Gawain South East. This acquisition, along with the recently announced equity increases in the Horne discovery and Hewett / Bacton, the latter with a proposed assumption of operatorship, continues to demonstrate our commitment to adding value at every opportunity in this core area.”

For further information contact:

Tullow Oil plc
Tel: +44-020 7333 6800
Tom Hickey - Finance Director
John Lander - Managing Director, TOUK Limited
www.tullowoil.com

Binns & Co PR Ltd
Tel: +44-020 7786 9600
Emma McCaffrey
Peter Binns
www.binnspr.co.uk

NOTES TO EDITORS

• The Thames fields comprise production not only from Thames itself, but also from the Yare, Deben, Bure and Wensum fields, with first production having commenced in 1986. The fields produce into a complex of three bridge-linked platforms, which also act as a production hub for other fields in the area, notably the Orwell and Gawain fields in each of which TOUK has 50% equity. The gas is processed on the platforms and then compressed before export to the Bacton terminal, 88km to the west, where TOUK recently agreed to increase its equity and plans to assume operatorship in Q4 2003.
• The Gawain South East exploration well (TOUK 50% equity) is located between the producing Gawain and Davy North fields and is expected to spud in early August.
• The net cash consideration payable to Eni on completion is estimated to be approximately £1 million

Post completion, co-venturers in Thames will be:

Tullow Oil UK Limited	66.67%
Superior Oil (U.K.) Ltd	123.33%
Centrica Resources Ltd	10.00%

• Tullow Oil plc is a UK registered company, quoted on the London and Irish stock exchanges, and one of the largest Independent Exploration and Production companies in Europe. Tullow Oil is a dynamic player in the international oil and gas industry. Its primary offices are in London (UK & Corporate) and Dublin (International Business).
• Tullow Oil has interests in 54 exploration and production licences spread over three main areas – Europe, South Asia and Africa and has regional offices in each area.