Well Test Results

Tullow Oil PLC 01 March 2007 News release Tullow Oil Plc - Kingfisher-1 Well Test Results 1 March 2007 - Heritage Oil, the operator of the Kingfisher-1 exploration well in Uganda, in which Tullow Oil plc ('Tullow') is a 50% partner, today issued the following press release: Calgary, Alberta, March 1, 2007 - Heritage Oil Corporation (TSX: HOC) today announced final results from the successful testing of all three intervals in the deeper horizon of the Kingfisher-1A well in Block 3A, Uganda. The three intervals tested, from between 2,260m to 2,367m, had a total net productive thickness of 44 metres and produced at a cumulative maximum flow rate of 9,773 bopd. Additionally, the test of the shallower interval reported in November 2006 produced at a rate of 4,120 bopd, resulting in an overall cumulative maximum flow rate of 13,893 bopd from the Kingfisher well. The tests may be summarised as follows: Depth Interval thickness Production Oil quality Flowing well head pressure (metres) (metres) (bopd) (API) (psig) Deeper intervals 2,344 21 2,965 32 240 2,290 12 2,254 31 157 2,260 11 4,554 32 360 44 9,773 Shallower interval* 1,783 10 4,120 30 221 Total 54 13,893 * Test undertaken in November 2006 The oil is good quality light (between 30degrees and 32degrees API) and sweet with a low gas-oil ratio and some associated wax. All of the above production flow rates were conducted through a one inch choke. The reservoirs are sandstones which have high permeability up to 2,300 milliDarcies. The Kingfisher prospect is a very large structural high that is expressed at surface on the bed of Lake Albert. Seismic data indicates an areal extent of up to 70 square kilometres for the Kingfisher prospect. This first exploration well only investigated a limited part of this large structure and did not reach the deepest objectives. Heritage is operator of and holds a 50% interest in Blocks 3A and 1 in Uganda, and has a 39.5% interest in Blocks 1 and 2 in the Democratic Republic of Congo. The total gross size of these holdings is in excess of 12,000 square kilometres and they occupy a very substantial part of the Albert Basin. Heritage's partner in these blocks is Tullow Oil. A map of the licenses, and the potential targets in Block 3A, is available on Heritage's website (www.heritageoilcorp.com). Looking forward to future Uganda work programs, Heritage has contracted to acquire two seismic surveys this year; a circa 325 square kilometre 3D program over the Kingfisher and Pelican structures in Block 3A and a circa 500 kilometre 2D survey in Block 1. Further drilling of the Kingfisher prospect will commence following the acquisition and interpretation of the 3D seismic survey. Efforts are currently being made to identify and secure a higher capacity rig capable of deeper drilling in order to explore the deepest objectives not penetrated by the Kingfisher well. In addition, initial plans are being developed to drill the offshore Pelican prospect next year. Tony Buckingham, Heritage's CEO stated 'The cumulative flow rate of 13,893 bopd from the Kingfisher well has surpassed our expectations. The test results indicate the outstanding potential of the Kingfisher discovery; substantially lowers the exploration risk of drilling other multiple targets in our licenses; and is another step closer to future production and commercial viability. Heritage is accelerating the work program to maximise the potential of what could be a world-class petroleum basin. All five wells drilled in the Albert Basin in the last 15 months have been oil discoveries, which we consider exceptional for a virgin onshore hydrocarbon basin and Kingfisher is the second well that has produced over 12,000 bopd under test. This is a very exciting time for Heritage, as these licenses could transform this Company.' For further information contact: Tullow Oil plc Citigate Dewe Rogerson Murray Consultants (+44 20 8996 1000) (+44 20 7638 9571) (+353 1 498 0300) 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 100 exploration and production licences across over 20 countries and focuses on three principal core areas: NW Europe, Africa and South Asia. Tullow's NW Europe 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 60% 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. Following the recently completed acquisition of Hardman Resources Limited, Tullow also has high impact exploration interests in French Guiana, Suriname and the Falkland Islands. For further information please refer to our website at www.tullowoil.com ENDS This information is provided by RNS The company news service from the London Stock Exchange

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