Relinquishment Report 1. Header · bp exploration (alpha) limited 17.13 silverstone cns limited 25 silverstone sns limited 50 49/21b area a - viper area conocophillips (u.k.) limited

Relinquishment Report

1. Header

License: P.039

Round: First

License Type: Traditional

Block: 49/21

Operator: ConocoPhillips

Partners in retained acreage

Block / Subarea Operator Equity Holder Interest 49/21a AREA A - INCLUDING VULCAN FIELD AREA

CONOCOPHILLIPS (U.K.) LIMITED ARCO BRITISH LIMITED 12.5

BP EXPLORATION (ALPHA) LIMITED 37.5

CONOCOPHILLIPS DEVELOPMENTS LIMITED 12.5

CONOCOPHILLIPS (U.K.) ALPHA LIMITED 12.5

CONOCOPHILLIPS (U.K.) LIMITED 25

49/21a VULCAN EAST SILVERSTONE SNS LIMITED ARCO BRITISH LIMITED 7.88


SILVERSTONE CNS LIMITED 25

SILVERSTONE SNS LIMITED 50

49/21b AREA A - VIPER AREA





EOG RESOURCES UNITED KINGDOM LIMITED 50

49/21b AREA B - INCLUDING SOUTH VALIANT FIELD


BP EXPLORATION BETA LIMITED 37.5


CONOCOPHILLIPS PETROLEUM LIMITED 25


Partners in retained acreage (cont.)

Block / Subarea Operator Equity Holder Interest 49/21b AREA B - VIPER AREA






49/21b AREA C - VIPER AREA


BRITOIL PUBLIC LIMITED COMPANY 17.13


CONOCOPHILLIPS LIMITED 9.25



49/21b AREA D - WEST EXCL. VULCAN & S. VALIANT





CONOCOPHILLIPS (U.K.) LIMITED 25

Work Programme Summary:

1st Round License awarded 17

th September 1964

Work Obligation: Seismic acquisition plus 6 wells

10 Exploration wells have been drilled to date resulting in 4 significant discoveries; Vulcan and

South Valiant, which came on-stream in 1998, Vulcan C which came on-stream in 2004 and

more recently Vulcan East drilled by Silverstone Energy Ltd in 2007. Of the other 6 other

exploratory wells, 2 were drilled to appraise S. Valiant and one (49/21-3) was a dry hole whilst

the other 3 encountered gas shows and were deemed to be non commercial.

2. Synopsis

License Status: Block part relinquished in 2009 as part of DECC’s 1st Round License Extensions

initiative

3. Exploration Activities

Seismic:

Block 49/21 was originally covered by 2D seismic acquired in 1972 by SSL and reprocessed by

Horizon Exploration in 1984. A subsequent 2D survey infilling the original was acquired in

1983 by SSL.

The most recent data available is a full 3D Ocean Bottom Cable survey performed in 1996

which was originally processed by Western Geophysical. It was time processed in 1997 and

underwent pre-stack depth migration in 2000. The seismic data is currently owned by PGL.

Wells drilled in relinquished area:

49/21-1: drilled by Signal in 1966, gas shows with H2S, open hole DST, no gas to surface. P&A.

49/21-3: drilled by Conoco North Sea Ltd in 1972, gas shows, open hole DSTs, no gas to

surface. P&A.

49/21-8A: drilled by Conoco North Sea Ltd in 2001, approx. 220ft tight gas bearing reservoir,

no valid RFTs due to supercharging, not tested, P&A.

49/21-9z: drilled by EOG Resources in 2004, no gas shows, logs indicate approx. 40ft tight gas

bearing reservoir, No RFT s, not tested. P&A

4. Prospectivity Analysis:

Reservoir:

The Rotliegendes reservoir in this Block is subdivided into 4 primary zones.

Zone Geology Rock Properties Avg. Thickness

A Fine grained aeolian

dune and sheet sands,

reworked interval at top

(Weissliegend)

8-10% porosity

typically <1mD air

permeability

120’ TVT

B Fine to occasionally

med. grained mixed

sand sheet / aeolian

dune and interdune

10-15% porosity

typically 1-15 mD air

permeability

115’ TVT

C Medium to coarse

grained aeolian dune

sequence – dry Erg

equivalent

10-18% porosity,

typically 10 – 1000mD

air permeability

275’ TVT

D Mixed Aeolian / Fluvial 10-15% porosity

typically 1-15 mD air

permeability

205’ TVT

Source: The primary source rock for the Rotliegendes Fields is the prolific Carboniferous Coal

Measures

Seal:

The overlying Zechstein salts and anhydrites provide top and side seal across the area

Trap Type:

The primary trap type throughout this area is either 4 way dip closure or 3 way with fault

closure

Horizons of interest:

The horizon of interest in this Block is comprised of aeolian sandstones of the Rotliegendes

Group. Reservoir quality is seen to be a function of lithotype, depth of burial and the limited

degree of diagenesis that the reservoir has undergone. The upper most Zones, A&B, are

generally of much poorer reservoir quality in terms of in-situ permeability compared to Zone C,

to such an extent that the latter has been the primary target for prospect evaluation. Zone C is the

most significant producing unit in the Vulcan and South Valiant Fields.

Remaining prospectivity:

10 Exploration wells have been drilled on the Block resulting in 4 commercial discoveries.

However the relinquished area of this Block includes the 4 non commercial wells mentioned

previously. Prospect evaluation has to date focused on there being sufficient structural closure in

order to develop the high deliverability Zone C within the gas column. Consequently structures

with columns greater than 300ft have been required in order to ensure Zones A & B are well

above the gas water contact. It is believed that from the recent reviews by ConocoPhillips,

together with a number of farminees, including EOG and Silverstone Energy there is no

prospectivity of the type just described, remaining in this area.

The enclosed Top Rotliegendes time structure map does show a remaining low relief closure in

the south east of the Block, but due to this lack of relief, it would only have Zone A and B

developed within closure and consequently would be a tight gas opportunity, requiring as a

minimum, additional stimulation in order to secure commercial gas rates.

5. Reserves Summary:

It is ConocoPhillips’ opinion that all commercially prospective accumulations have now been

drilled within 49/21.

6. Clearance:

ConocoPhillips confirms that we along with BP and EOG agree that DECC is free to publish

any or all data contained here-in.

7. Maps & Figures:

Location Map

License P.039

Block 49/21

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49/21-3

49/21-1

49/21-8A

49/21-10

49/21-9Z

436000 440000 444000

436000 440000 444000

X, [m]

5892000

5896000

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Y, [m

]

436000 440000 444000

436000 440000 444000

X, [m]

5892000

5896000

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Y, [m

]

434000 436000 438000 440000 442000 444000 446000

434000 436000 438000 440000 442000 444000 446000

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Time Structure Map – Block 49/21

49/21-8A

Vulcan

49/21-3

49/21-9z

2’ 00”E 2’ 12”E

53’ 10”N

53’ 20”N

49/21-10z

Vulcan East

49/21-5

49/21-1

South Valiant

Line of Section

49/21-7

Illustrative Seismic Time line – Block 49/21

49/21-1 49/21-8A 49/21-5

Top Chalk

Rot Halite

Top Zechstein

Top Winterton

Top BasalAnhydrit

Top Rotliegendes

SW NE

Relinquishment Report 1. Header · bp exploration (alpha) limited 17.13 silverstone cns limited 25 silverstone sns limited 50 49/21b area a - viper area conocophillips (u.k.) limited

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