Licence P 994 Relinquishment Report HEADER Licence: P 994 Licence Round: 18th Round Licence Type: Traditional Block(s): 22/27b, 22/28b Equity: GDFBritain Ltd (Operator) 50% E.ON Ruhrgas 50% WORK PROGRAMME SUMMARY Original License award work programme 19th June 2000: Reprocess 203km2 of 3d seismic data using Pre Stack Depth and Time Migration before expiry of one year from date of commencement of license , or such longer period as the Minester may agree: and Drill one exploration well to 5500m to test the Carisbrooke prospect contingent upon the evaluation of the reprocessed seismic Additional agreed work programme for 2 year extension Letter 8th June 2005 Acquire long cable 3D seismic over license (58 km sq) long offset data over the remaining area: and Make a Drill or drop decision by 22nd December 2006. SYNOPSIS This report is to support the full relinquishment of the license at the end of licence term. A 54 % relinquishment was made in June 2005 . The License was awarded a two year extension (Letter from DTI 8th June 2005 ) on the initial term due to the withdraw of the original operator and assignment of Operatorship of GDF Britain Ltd. A further three month extension was given until the end March 2007, to complete a Rock Physics study of the area.

EXPLORATION ACTIVITY In 2006, as agreed with the BERR (DTI) and in lieu of a contingent well, the partnership underwrote the acquisition and processing of a CGGVeritas long-offset 3D seismic survey over the full licence area to try to get a better understanding of the deep Carisbrooke Fulmar Sandstone prospect. These data were used to carry out both a new GDF Britain qualitative structural interpretation of block prospectivity and as input to a detailed quantitative third party rock physics study. PROSPECTIVITY ANALYSIS Key wells The key wells for this licence are the;- 22/28-2RE well drilled by BP in 1989. This well TD at 17968ft MD (5477m) within the Triassic Skagerrak formation. The well encountered over 170ft of hydrocarbon column in the Fulmar and Pentland formations. The GWC was picked at 17255ft TVDSS based on log interpretation. As single DST flowed at 3.55mmscf/d with 412 bbl/d condensate. 22/27a-2 drilled by Ranger Oil in 1986, the well encountered over 450ft of gross hydrocarbon column in the Fulmar and Pentland formations. The well TD at 17246 ft MD (5256m) within the Triassic. DST of the Fulmar section tested at a rate of 9.4mmscf/d with 1020bbl/d condensate. 22/27a-1 drilled by Ranger Oil in 1984 the well TD at 16585ft MD (5055m) within the Pentland. Drilling problems meant that wireline logs were unable to get below 15488ft MD (4721m). The well encountered Fulmar equivalent sands but these were water wet. The well did encounter hydrocarbons in the Upper Cretaceous Herring Formation. This was tested and flowed 500bopd of 39 API oil . 29/2b-5 drilled by Enterprise in 1990. The well TD at 16594ft MD (5057m) within the Triassic. The well encountered oil and gas shows in the Fulmar, Pentland and Triassic section. The Fulmar equivalent was cored and proved to be dominated by poor quality lower shoreface sands with net only 50 ft net sand. Trap GDFBritain Ltd, 2006/7 Interpretation The PSTM volume of the CGGVeritas long-offset 3D seismic survey shows a significant improvement in quality over previous surveys, most noticeably in terms of noise reduction and imaging in the deeper section, but reflection quality remains poor at the target Fulmar Sandstone level.

The new GDF Britain interpretation has confirmed the Carisbrooke prospect as a faulted/dip closed feature with a small horst block at its core. The major eastern margin fault provides excellent up thrown seal potential to the East and North of the structure but throw decreases to the South East. A salt structure may be present in the South East where the throw of the eastern margin fault decreases, providing possible additional or alternative seal potential in this area.

Downthrown fault sealing is required in the South, and the West for the upside case, of the Carisbrooke structure and represents a significant risk to the validity of the trap in these areas. Fulmar to Pentland sandstone juxtaposition is considered likely across this western margin fault.

East – West CGG Veritas seismic section over the Carisbrooke Prospect

North - South CGG Veritas seismic section over the Carisbrooke Prospect A “soft” amplitude anomaly, not seen on any of the previous seismic surveys in the area, can be observed at the interpreted Fulmar Sandstone level on the CGGVeritas 3D seismic data. This anomaly is present on both the normal amplitude and Relative Acoustic Impedance volumes, with the clearest response restricted to the small faulted horst core of the structure. Elsewhere the response is more ambiguous and shows a much poorer correlation with structure. GDFBritain Ltd, Rock Physics Study - IKON 2007 A detailed Rock Physics study was carried out by IKON in 2007 to determine more precisely the nature of this anomaly response, using both the surrounding well data and utilising the full offset range of the CGGVeritas 3D dataset. The

results of this study have proved inconclusive with a number of possible scenarios fitting the observed response. Additional Trap Studies ChevronTexaco, Fault Seal Risking in the Carisbrooke Exploration Prospect (22/27 and 22/28). UK Central North Sea (P994) - RDR Ltd University of Leeds January 2004

East – West geoseismic section over the Carisbrooke Prospect

Reservoir The prime reservoir target for the Carisboorke prospect is the Upper Jurassic Fulmar Sandstone, proven to be hydrocarbon bearing in the 22/27a-2 and 22/28b-2RE wells, but their thickness and quality is variable across the area. Results of the petrophysical analysis for some of the key wells is given below.

Other Reservoir Studies Texaco, A biostratigraphic Analysis of Selected Intervals in UKCS Central North Sea Wells 22/27a-1, 22/27a-2 and 29/2b-5 S. Duxbury November 1998 GDF Britain Ltd, Revision of Block 22/27 Jurassic Correlation and Palaeogeographis- BIostratigraphic Report - Ichron November 2006

Pay Cutoff Curve Name Disc Cutoffno PHIEQ >= 0.150 Approx. equivalent to 0.5 mDyes SWQ <= 0.600no VCLQ <= 0.500

Well Name Zone NameTop Depth

(ft MD)

Bot Depth (ft

MD)

Gross Interval

ft

Gross Interval

m

Net Res Int (ft TVD)

Res/Gross (Res)

Avg Phi (Res)

Net Pay Int (ft TVD)

Avg Phi (Pay)

Avg Net Sw (Pay)

22/27A- 02 FULMAR FM 16222.0 16623.0 401.0 122.2 98.5 0.246 0.194 68.5 0.201 0.37322/28B- 02RE FULMAR FM 17017.0 17103.0 86.0 26.2 52.0 0.605 0.171 48.0 0.171 0.35529/02B- 05 FULMAR FM 15775.0 16037.0 262.0 79.9 50.0 0.191 0.169 16.5 0.179 0.506

Net Reservoir Properties Net Pay Properties

Source The presence of hydrocarbons in nearby wells, and the Banff field to the South, indicates that the Kimmeridge Clay should be mature for wet gas generation in the region of the Carisbrooke prospect. Seal The top seal is expected to be afforded by the overlying Heather Shales, which are interpreted to be thickly developed over the prospect. Some inter-bedded Heather turbidite sandstones could also be present in this interval, which may have an impact on the position of the ultimate top seal. Side seal is a key risk with down thrown Lower Creataceous Crommer Knoll or Upper Jurassic Heather Shales juxtaposed to the East and up thrown Pentland or Triassic sands and shales to the South and West. Risk – chance of success Primary risks for the Carisbrooke prospect is the lateral side seal together with reservoir presence and quality. Closure, Source, Migration, Timing and Top Seal are considered to be a generally low risk. Volumes Carisbrooke Volumes

P90 P50 P10 MeanGIIPGas bcf 32 51 87 56

ReservesGas bcf 19.2 30.6 52.6 33.6Condensate mmbc 2.1 3.5 6 3.8Total mmboe 5.5 8.9 15.3 9.9 Other Prospectivity No additional prospectivity has been identified elsewhere on the licence, either in the Fulmar Sandstone or in other possible reservoir intervals.

Summary Reservoir Fulmar sandstones are found in a number of nearby wells but

quality and thickness is variable and often poor Source The presence of hydrocarbons in nearby wells, and the Banff field

to the South, indicates that the Kimmeridge Clay should be mature for wet gas generation in the region of the Carisbrooke prospect.

Seal Top seal is expected to be afforded by the overlying Heather

Shales, which are interpreted to be thickly developed over the prospect. Some inter-bedded Heather turbidite sandstones could also be present in this interval, which may have an impact on the position of the ultimate top seal. Side seal against up thrown Pentland and Triassic sand shales to the south and west are a key risk

Trap The Carisbrooke prospect is primarily a tilted fault block structure

that relies on fault trapping to the East, North and South, and dip and/or fault trapping to the West. A small salt feature in the South East corner of the prospect may also play a part in the trapping geometry.

Risk Although Fulmar Sandstone reservoir has been encountered in

nearby wells quality is generally poor and studies indicate a likely similar poor quality for the Carisbrooke prospect. Trap risk increases to the South and West where cross fault reservoir to reservoir leakage is likely away from the very small core horst area of the prospect.