ABERDEEN, Scotland, July 7, 2010 /PRNewswire/ -- GDF SUEZ EP UK Ltd, operator of the Cygnus gas field, is pleased to announce a second successful appraisal well (44/12a-5) in the south western area of the gas field located in the UK southern North Sea.

This success completes the full appraisal of the Cygnus field within its current boundary. Analysis of the results from the discovery well and six appraisal wells, together with 3-D seismic evaluations, have led to a preliminary ultimate recovery estimate of approximately 500 billion standard cubic feet of natural gas - up to 1 trillion standard cubic feet in the high case. This latest success underlines Cygnus' position as one of the most significant undeveloped gas fields in the United Kingdom Continental Shelf.

Rene Montaz-Rosset, Managing Director of GDF SUEZ EP UK Ltd commented: In the past eighteen months, four appraisal wells have been drilled and all have been successful in meeting and exceeding pre-drill expectations. The participants are now moving swiftly towards development and look forward to realising the exciting potential of this field.

The licence participants in the Cygnus field are GDF SUEZ EP UK, the operator, together with Centrica plc and Endeavour Energy UK Limited. Following the successful appraisal of the eastern area in 2009 and the western area in 2010, the participants are pursuing an optimised field development plan for Cygnus. This comprises a two-phase approach, with an enlarged first phase to include the full development of the eastern area and a phase two development of the western area. Sanction is scheduled for 2011, with first gas scheduled for 2013.

The Cygnus participants have also been awarded Licence P1731 by the Department of Energy and Climate Change (DECC). Undrilled prospective fault blocks, which are likely to extend the Cygnus field, have been identified within the licence area. These blocks will be appraised in due course.

Well 44/12a-5 achieved a stabilised flow rate of 29 million standard cubic feet per day (MMscfpd) from 94 feet of perforations in the Leman interval.

Notes to editors:

- The Cygnus field is located within UK Continental Shelf (UKCS) Blocks 44/12a and 44/11a in the UK southern North Sea, 15 km north west of the Tyne field. Cygnus is a large multi fault block accumulation discovered in 1988 by the 44/12a-1 exploration well, which found gas bearing Leman reservoir in what is now known as Fault Block 1. - GDF SUEZ EP UK Ltd is operator of Cygnus Field (Licence P1055) with a 38.75% interest. The licence participants are Centrica with a 48.75% interest and Endeavour Energy UK Limited with a 12.5% interest. - GDF SUEZ EP UK Ltd is also operator of Licence P1731 with a 34.48% interest. The licence participants are Centrica with a 48.28% interest and Endeavour Energy UK Limited with a 17.24% interest.

About GDF SUEZ EP UK Ltd

An established operator in the UK, GDF SUEZ EP UK Ltd is involved in the exploration and production of gas in the southern North Sea, central North Sea and west of Shetland. In total, the company employs 90 staff at the London head office and the operations centre in Aberdeen. In the UK GDF SUEZ EP holds 50 exploration licences (24 as an operator), 22 production licences and 20 producing fields (two as an operator) located in the UK North Sea. With the ongoing Cygnus and Juliet development projects the proportion of operated production will rise to 50% by 2013. A total of 10 million boe per year is produced by GDF SUEZ EP UK.

About GDF SUEZ

One of the leading energy providers in the world, GDF SUEZ is active across the entire energy value chain, in electricity and natural gas, upstream to downstream. It develops its businesses (energy, energy services and environment) around a responsible-growth model to take up the great challenges: responding to energy needs, ensuring the security of supply, fighting against climate change and maximizing the use of resources. GDF SUEZ relies on diversified supply sources as well as flexible and high-performance power generation in order to provide innovative energy solutions to individuals, cities and businesses. The Group employs 200,650 persons worldwide and achieved revenues of EUR79.9 billion in 2009. GDF SUEZ is listed on the Brussels, Luxembourg and Paris stock exchanges and is represented in the main international indices: CAC 40, BEL 20, DJ Stoxx 50, DJ Euro Stoxx 50, Euronext 100, FTSE Eurotop 100, MSCI Europe and ASPI Eurozone.

SOURCE: GDF SUEZ ESOURCE: P UK Ltd

CONTACT: Contacts: Ruth Potter, GDF SUEZ EP UK, +44(0)203-122-1424,ruth.potter@gdfsuezep.co.uk ; Jackie Robinson, BIG Partnership,+44(0)7711-281915, jackie.robinson@bigpartnership.co.uk .