Licence P1675 Block 48/7e Relinquishment Report

Licence P1675 Block 48/7e Relinquishment Report

Licence P1675, block 48/7e, Relinquishment Report - Centrica Energy Upstream 1 General 1 2 Synopsis 2 3 Exploration Activities 2 4 Prospectivity Analysis 2 5 Reserves Summary 4 6 Clearance 4

List of figures 1.1 Licence P1675, block 48/7e location.............................................. 1 4.1 Dip Line across Hoton Field & Hoton-East Prospect.................................. 3 4.2 Block 48/7e Prospectivity........................................................ 4

List of tables 1.1 Licence Summary.............................................................. 1

Licence P1675, block 48/7e, Relinquishment Report - Centrica Energy Upstream - 1 General Page 1 1 General Introduction This report documents the full relinquishment of Licence P1675, block 48/7e, see Fig. 1.1. Fig. 1.1 Licence P1675, block 48/7e location Table 1.1: Licence Summary Licence Number Licence Round Licence Type P1675 25th Traditional Block Number(s) 48/7e Operator/Partner % Centrica Resources 90% / Volantis Exploration 10% Commitments / Restrictions This is a traditional licence with a start date of 12th February 2009. The agreed work programme within Schedule 1 states that by the 11th February 2011 the licensee must make a firm commitment to complete Part 2 of the work programme, or the licence will automatically expire. The work programme was a two year drill or drop commitment where the licensee shall either drill one well to 3500m or to the Leman sandstone, whichever is the shallower or elect to allow the licence to automatically cease. At this time Centrica and its partner see no economic prospectivity in the licence and elect to let the licence cease. Document last updated 02-02-2011 16:48 GMT

Licence P1675, block 48/7e, Relinquishment Report - Centrica Energy Upstream - 2 Synopsis Page 2 2 Synopsis Licence P1675 containing block 48/7e was awarded in the 25 th round with a start date of 12th February 2009. The licence is situated in the Sole Pit basin in the Southern North Sea, directly to the east of the Hoton field. Centrica and its partner wish to relinquish this licence in its entirety. 3 Exploration Activities Wells Drilled There are no wells within the licence. The 48/7-4 well was drilled just outside the licence in 48/7b (P138) on the Hoton East opportunity by BP in 1977. Despite strong gas shows the DST failed to flow and the well was plugged and abandoned with gas shows. The reservoir quality was shown to be tight but better than the nearby Hoton field. Seismic Database The basis of the interpretation over the licence and the surrounding area was a combination of five 3D surveys; Hoton, Galleon, Babbage, Block 48/7-8 and the Centrica Quad 48 PreSDM stretched back to time. The latter was picked across the area in detail and merged with the other 3Ds. 4 Prospectivity Analysis Reservoir The main reservoir recognised and present within the licence is the Permian Leman sandstones. Reservoir quality/effectiveness is the key issue in this area, it is generally tight with permeabilities invariably less than 1mD, although aeolian intervals can provide higher quality reservoir. Offset wells indicate that there is an overall thinning of the Leman sandstone towards the NE. Here the aeolian prone, Unit D, becomes thinner than over the nearby Hoton and Sloop fields. The 48/7-4 well showed that reservoir quality is tight with a permeability range of 1-5mD. No GWC is apparent in the logs and all RFT attempts failed. The neighbouring Hoton field has an average porosity of 13% and permeability of 0.01mD. There is also a risk in the Hoton East prospect that the potential effective reservoir may lie below the GWC. Source Carboniferous, Westphalian coal measures are present and mature providing gas for any closure in the area.

Licence P1675, block 48/7e, Relinquishment Report - Centrica Energy Upstream - 4 Prospectivity Analysis Page 3 Seal Zechstein evaporites provides the regional seal in this area. Where the Silverpit Formation is shale prone this can act as the top seal as seen in West Sole, Cleeton and Ravenspurn North. It is questionable as to whether the Silverpit will act as a top seal where it splits the Leman Sandstone into upper and lower reservoir units and is sand prone such as in the Hoton East area. Trap The structure has shallow relief and as a consequence the hydrocarbon column exists in the poorer quality Upper Leman. It has been concluded that the structure is too small to be economically viable (Fig. 4.1). Dip Line Across Prospect Hoton-East SW Hoton Hoton survey 48/6-2848/7-8 48/7e block Centrica Q48 survey NE TWT 0.5 Mid-Late Jurassic Lias 1.0 Zechstein Haisborough 1.5 Rotliegendes Bacton Carboniferous Hoton Hoton East Fig. 4.1 Dip Line across Hoton Field & Hoton-East Prospect 5km Remaining Prospectivity No remaining economic prospectivity that would justify a well being drilled in this licence has been identified (Fig. 4.2).

Licence P1675, block 48/7e, Relinquishment Report - Centrica Energy Upstream - 4 Prospectivity Analysis Page 4 Block 48/7e Prospectivity Cobra Prospect Hoton Hoton East Prospect 48/7e 5km Fig. 4.2 Block 48/7e Prospectivity 5 Reserves Summary GIIP Calculations No economically viable prospectivity has been identified within the licence. 6 Clearance Publication Clearance All 3 rd party ownership rights (on any contained data and/or interpretations) have been considered and appropriately cleared for publication purposes.