BLVN.L Regulatory News (BLVN)

9 June 2011

Bowleven plc ('Bowleven' or 'the Company')

Sapele well testing update

Sapele-1 sidetrack (Sapele-1ST), Block MLHP-5, Etinde Permit, Cameroon

Bowleven, the West Africa focused oil and gas exploration group traded on AIM is pleased to announce the results of testing activities at the Sapele-1ST appraisal well drilling in the Douala Basin, offshore Cameroon. Drill stem testing was performed within the Deep Omicron interval at Sapele-1ST and a light oil flowed on test.

Highlights

·; Stabilised flow rate of 3,101 boepd produced on test at Sapele-1ST

·; High quality light oil (39.2 degree API) produced on test; oil quality and gas-oil ratio comparable to that encountered at the original Sapele-1 well

·; Testing programme underway at Sapele-2

Sapele-1ST update

The principal objective of Sapele-1ST was to appraise the Deep Omicron oil discovery encountered in the Sapele-1 exploration well.

As previously announced, the Sapele-1ST well encountered log evaluated net pay conservatively estimated to be approximately 10 metres within the Deep Omicron interval, based on conventional wireline logs. The well was drilled to a TVD of 3,634 metres (4,483 metres measured depth) in water depths of around 25 metres approximately 2 kilometres south east of the Deep Omicron oil discovery in the original Sapele-1 vertical well.

Drill stem testing at Sapele-1ST was conducted over a 71 metre perforated interval. The interval flowed at a stabilised rate of 2,023 bopd of 39.2 degree API oil and approximately 6.47 mmscfd of associated gas on a 56/64 inch choke.

The interval tested at Sapele-1ST correlates on seismic with the equivalent Deep Omicron interval drilled by the original Sapele-1 well, where better developed sands were encountered. The Sapele-1 well had a confirmed oil pressure gradient at Deep Omicron and oil samples were obtained during logging activities. The oil quality, gas-oil ratio and pressures measured on test at Sapele-1ST are comparable to the samples and pressures taken at Sapele-1.

Forward plan

Due to the stratigraphic nature of the Omicron discoveries further analysis and appraisal is required to delineate the fields and to assess the implications for resource estimates and potential development options for these discoveries. The productivity demonstrated by the Deep Omicron test at Sapele-1ST is a key step forward. In addition, a testing programme is ongoing at Sapele-2, drilled to appraise both the Lower and Deep Omicron discoveries, and the results from this will be integral to this process.

As planned the Noble Tommy Craighead rig is being released after Sapele-1ST testing for a mandatory recertification process.

A map indicating the locations of the Sapele-1ST and Sapele-2 wells is available on our website www.bowleven.com under the heading "Presentations"; the presentation is titled "Sapele drilling locations".

An update announcement and conference call are planned on completion of the full test programme at Sapele-2, which is expected in around two to three weeks. Further announcements on drilling activities will be made as appropriate.

Kevin Hart, Chief Executive of Bowleven plc, commented:

"Bowleven is delighted to announce its first oil flow test in the Douala Basin, offshore Cameroon, at Sapele-1ST. The flow rates produced at Sapele-1ST are believed to be commercial. These are highly encouraging, particularly so given that better sand development was encountered in the original Sapele-1 well at the equivalent level, with good indications of comparability between the two. Whilst further appraisal is required to fully understand the resource potential, we are encouraged by the result and the likelihood of a commercial development at Sapele given the shallow water depths. Our acreage in Cameroon shows increasing potential as we focus on our dual strategy of targeting high impact exploration potential in the Douala Basin and converting resources to reserves."

ENQUIRIES

For further information please contact:

Bowleven plc

Kevin Hart, Chief Executive 00 44 131 524 5678

Kerry Crawford, Head of Investor Relations 00 44 131 524 5678

Brunswick Group LLP

Patrick Handley 00 44 207 404 5959

Natalia Erikssen

RBS Hoare Govett

Stephen Bowler 00 44 207 678 8000

Jamie Buckland 00 44 207 678 8000

Notes to Announcement:

(1) The technical information in this release has been reviewed by Ed Willett, who is a qualified person for the purposes of the AIM Guidance Note for Mining, Oil and Gas Companies. Ed Willett, Exploration Director of Bowleven plc, is a geologist and geophysicist, a Fellow of the Geological Society (FGS) and a member of the Petroleum Exploration Society of Great Britain (PESGB) with over 25 years' experience in oil and gas exploration and production.

(2) The information contained in this release reflects the views and opinions of Bowleven as operator and has not been reviewed in advance by the Etinde Permit joint venture partners.

Notes to Editors:

Bowleven is a West Africa focused oil and gas exploration group, based in Edinburgh and traded on AIM since 2004. Bowleven's strategy is focused on creating and realising material value through exploration led organic growth.

Bowleven holds equity interests in 7 blocks in Cameroon and Gabon, with 4 blocks located offshore in shallow water, and 3 onshore, with 6 of these blocks operated by Bowleven. The Etinde Permit (Bowleven 75%; Vitol 25%) comprises approximately 2,316 km² of exploration acreage located across the Rio del Rey and Douala Basins. There is an extensive multi-well exploration and appraisal drilling programme ongoing on the Etinde Permit during 2011.

GLOSSARY OF TERMS:

The following are the main terms and abbreviations used in this announcement:

For the purposes of this announcement, 6 mscf of gas has been converted to 1 boe.