P039

Relinquishment Report
1. Header
License:
Round:
License Type:
Block:
Operator:
P.039
First
Traditional
49/21
ConocoPhillips
Partners in retained acreage
Block / Subarea
Operator
Equity Holder
49/21a AREA A INCLUDING VULCAN
FIELD AREA
CONOCOPHILLIPS (U.K.)
LIMITED
ARCO BRITISH LIMITED
12.5
BP EXPLORATION (ALPHA) LIMITED
CONOCOPHILLIPS DEVELOPMENTS
LIMITED
37.5
CONOCOPHILLIPS (U.K.) ALPHA LIMITED
12.5
CONOCOPHILLIPS (U.K.) LIMITED
49/21a VULCAN EAST
49/21b AREA A - VIPER
AREA
49/21b AREA B INCLUDING SOUTH
VALIANT FIELD
SILVERSTONE SNS
LIMITED
CONOCOPHILLIPS (U.K.)
LIMITED
CONOCOPHILLIPS (U.K.)
LIMITED
Interest
12.5
25
ARCO BRITISH LIMITED
7.88
BP EXPLORATION (ALPHA) LIMITED
17.13
SILVERSTONE CNS LIMITED
25
SILVERSTONE SNS LIMITED
50
ARCO BRITISH LIMITED
12.5
BP EXPLORATION (ALPHA) LIMITED
CONOCOPHILLIPS DEVELOPMENTS
LIMITED
12.5
CONOCOPHILLIPS (U.K.) ALPHA LIMITED
EOG RESOURCES UNITED KINGDOM
LIMITED
12.5
ARCO BRITISH LIMITED
12.5
BP EXPLORATION BETA LIMITED
CONOCOPHILLIPS DEVELOPMENTS
LIMITED
37.5
12.5
50
12.5
CONOCOPHILLIPS PETROLEUM LIMITED
25
CONOCOPHILLIPS (U.K.) ALPHA LIMITED
12.5
Partners in retained acreage (cont.)
Block / Subarea
Operator
Equity Holder
49/21b AREA B - VIPER
AREA
CONOCOPHILLIPS (U.K.)
LIMITED
ARCO BRITISH LIMITED
12.5
BP EXPLORATION BETA LIMITED
CONOCOPHILLIPS DEVELOPMENTS
LIMITED
12.5
CONOCOPHILLIPS (U.K.) ALPHA LIMITED
EOG RESOURCES UNITED KINGDOM
LIMITED
12.5
49/21b AREA C - VIPER
AREA
49/21b AREA D - WEST
EXCL. VULCAN & S.
VALIANT
CONOCOPHILLIPS (U.K.)
LIMITED
CONOCOPHILLIPS (U.K.)
LIMITED
Interest
12.5
50
ARCO BRITISH LIMITED
7.88
BRITOIL PUBLIC LIMITED COMPANY
CONOCOPHILLIPS DEVELOPMENTS
LIMITED
17.13
CONOCOPHILLIPS LIMITED
9.25
CONOCOPHILLIPS (U.K.) ALPHA LIMITED
EOG RESOURCES UNITED KINGDOM
LIMITED
7.88
ARCO BRITISH LIMITED
12.5
BP EXPLORATION BETA LIMITED
CONOCOPHILLIPS DEVELOPMENTS
LIMITED
37.5
CONOCOPHILLIPS (U.K.) ALPHA LIMITED
12.5
CONOCOPHILLIPS (U.K.) LIMITED
7.88
50
12.5
25
Work Programme Summary:
1st Round License awarded 17th 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
A
B
C
D
Geology
Fine grained aeolian
dune and sheet sands,
reworked interval at top
(Weissliegend)
Fine to occasionally
med. grained mixed
sand sheet / aeolian
dune and interdune
Medium to coarse
grained aeolian dune
sequence – dry Erg
equivalent
Mixed Aeolian / Fluvial
Rock Properties
8-10% porosity
typically <1mD air
permeability
Avg. Thickness
120’ TVT
10-15% porosity
typically 1-15 mD air
permeability
115’ TVT
10-18% porosity,
typically 10 – 1000mD
air permeability
275’ TVT
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
436000
436000
434000
440000
440000
438000
444000
444000
442000
446000
-150
0
-1
60
0
0
0 49/21-5
5
-1
-140
0
-1
50
0
5898000
0
-1300
-140
0
00
-13
5896000
5896000
5894000
-12
00
-160
0
-140
-1 2
00
-1200
00
0
- 1200
0
-1600
5900000
5900000
0
-1
5
-130
5896000
5896000
50
-13
00
-1200
49/21-7
5894000
-1
Vulcan
49/21-10z
Vulcan East
-14
00
0
40
-1
00
-13
49/21-10
5900000
5900000
-1
30
0
-1200
-120
49/21-3
-1600
5902000
00
-14
0
-120
49/21-3
5902000
49/21-9Z
-130
0
0
70
-1
00
00
-16
- 13
00
-14
00
5904000
5904000
49/21-9z
-15
5904000
5904000
-1
-1 500
50
0
5906000
Line of Section
0
20
-1
Y, [m]
South Valiant
00
-17
5906000
-14
00
0
20
-1
5898000
- 15
00
-1
50
0
5908000
5908000
50
5908000
5908000
-1
00
-1700
-1
6
0
-1600
5910000
5910000
53’ 20”N
-1200
49/21-8A49/21-8A
0
20
-1
49/21-1
53’ 10”N
2’ 00”E
434000
2’ 12”E
436000
436000
438000
0
1000
440000
440000
X, [m]
3000
2000
1:100000
Time Structure Map – Block 49/21
442000
4000
5000m
444000
444000
446000
5890000
5890000
5892000
5892000
5892000
5892000
49/21-1
Illustrative Seismic Time line – Block 49/21
SW
49/21-1
49/21-8A
49/21-5
NE
Top Chalk
Top Winterton
Top BasalAnhydrit
Rot Halite
Top Zechstein
Top Rotliegendes