BHP BILLITON PETROLEUM LIMITEDBHP Billiton Petroleum Limited UK Production Unit – Liverpool Bay Relinquishment Report for P710: 110/13a 3 of 7 A west-east seismic line through the

BHP BILLITON PETROLEUM LIMITED

Liverpool Bay

Relinquishment Report for Licence P710 (110/13a) Kappa Discovery Area

24th March 2011

BHP Billiton Petroleum Limited UK Production Unit – Liverpool Bay

Relinquishment Report for P710: 110/13a

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P710 – 110/13a (Kappa Discovery Area) Licence Relinquishment Report

1 Header

Licence Number: P710

Licence Round: 11th Round

License Type: Fallow Discovery

Block: 110/13a

Operator/Partner %: BHP Billiton Petroleum Great Britain Ltd

Work Programme Summary:

Merging and reprocessing of 1085km2 of 3D seismic data over block 110/13 and the surrounding area.

2 Synopsis

The discovery well 110/13-17 was drilled in 1994 and determined to be uncommercial. The well tested the Kappa prospect in the north-eastern corner of block 110/13a. The well is located approximately 9 km north-east of the Hamilton field and 5km east of the Hamilton North field. ConocoPhillips’ Asland discovery lies immediately to the east in Block 110/14. Water depth is 83 ft.

The discovery was listed as Fallow B in 2004 for relinquishment by 31st December 2006. The DTI then agreed to await the outcome of the delayed 24th Round Licence award and the discovery was listed as Fallow B for relinquishment by 31st December 2007.

It was then amended to B Reused on the basis that the area was included in BHP Billiton’s seismic reprocessing programme over 110/12 and 110/13 through 2008 and 2009, Figure 1.

3 Exploration Activities

CGGVeritas merged and reprocessed four existing seismic datasets over 110/12 and 110/13, these were processed through both PreSTM and PreSDM sequences. The reprocessing resulted in a significant improvement in data quality compared to the previous data; fault definition and stratigraphic resolution were markedly superior to the vintage data.

The Kappa area has been re-interpreted using the reprocessed data volumes and an updated assessment has been completed.

4 Prospectivity Analysis

The Kappa discovery was made in the Triassic Sherwood Sandstone Group, the regional stratigraphy is shown in Figure 2. As in other Liverpool Bay fields the reservoir is characterised by excellent permeability sands deposited by aeolian and fluvial processes.

The trap is a horst block, fault bounded on all sides with some closure provided by dip to the north-west (Figure 3). The seal is provided by the Mercia Mudstone Group.

The 110/13-17 well encountered a 58ft gas column in the Triassic Ormskirk Sandstone Formation at a depth of 2218 ft TVDSS with a gas water contact at 2276 ft TVDSS.

The best reservoir characteristics are associated with the aeolian sands which show high porosity and high permeability values (generally greater than 1 Darcy).



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A west-east seismic line through the Kappa discovery and the Asland discovery (well 110/14-2) in block 110/14 is shown in Figure 4.

To the south of Kappa is the Rho prospect, this is a very similar fault bounded horst block. This structure has the potential to trap greater volumes than Kappa but this is considered unlikely given the large column height that would be required.

5 Reserves Summary

GIIP (bscf) Gas

Low Mid High

Kappa 0.31 1.11 3.49

Rho 0.37 3.19 16.57

6 Clearance

BHP Billiton Petroleum and ENI give permission to publish this relinquishment report.

7 Maps and Figures

BHP Billiton Petroleum LimitedUK Production Unit – Liverpool Bay


Figure 1: 3D Seismic Data Reprocessing Area (Block 11/13 and

BHP Billiton Petroleum Limited Liverpool Bay


3D Seismic Data Reprocessing Area (Block 11/13 and surrounding area)



Figure 2: Stratigraphy of the southern Liverpool Bay area



Figure 3: Top Ormskirk Depth Map





Figure 4: West-east seismic line through the Kappa and Asland Discoveries



through the Kappa and Asland Discoveries

Documents

BHP BILLITON PETROLEUM LIMITEDBHP Billiton Petroleum Limited UK Production Unit – Liverpool Bay Relinquishment Report for P710: 110/13a 3 of 7 A west-east seismic line through the