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Table 3.
Average content of non-clay minerals in percentage of bulk composition in mudrocks with palaeosols in the
Lunde Formation (L12-L01) and the Statfjord Group (S5-S1), recorded from Snorre Field wells 34/7-P-13, 34/7-P-18,
34/7-P-28, 34/7-P-29, 34/7-P-33 and 34/7-A-4H (Saigal & Nystuen, in Adestål, 2002).
Unit
Number of samples
Quartz
K-feldspar
Plagioclase
Calcite
Dolomite
Siderite
S1
5
46.6
3.8
2.0
0.1
0.0
3.7
S2
4
26.6
5.9
10.4
0.3
0.2
0.2
S3
13
45.6
8.9
8.8
0.4
1.4
1.1
S4
6
33.4
8.5
25.3
1.1
9.2
0.1
S5
3
31.6
2.4
0.4
0.1
0.2
0.3
L01
2
13.3
2.2
18.5
0.8
0.2
0.6
L02
23
28.4
6.6
19.4
1.5
5.5
0.1
L03
12
20.8
5.4
22.2
21.4
1.9
0.3
L04
14
18.5
6.6
34.2
8.6
6.2
0.6
L05
6
23.1
7.8
19.5
0.7
5.8
0.1
L06
7
23.6
7.2
19.8
5.1
5.3
0.1
L07
31
21.8
10.1
20.5
1.2
2.4
0.0
L08
17
21.1
5.9
18.8
22.8
2.4
1.1
L09
12
14.6
12.1
25.0
17.4
1.0
1.8
L10
15
14.5
6.3
18.2
28.9
11.0
1.4
L11
7
20.2
7.1
22.4
1.8
0.7
0.0
L12
5
18.9
8.3
19.5
3.0
0.0
0.0
Table 4.
Average content of clay minerals in mudrocks within allostratigraphic intervals L12-L11, L10-L05, L03-L01 in
the Lunde Formation (L12-L01) and S5-S3 and S1 in the Statfjord Group. From wells 34/4-C-6 H, 34/4-9S, 34/7-1, 34/7-3,
34/7-9, 34/7-P-8, 34/7A-3 H, 34/7A-9 H, 34/7-P-14.
Allostrati-
graphic units]
Swelling mixed-
layer (ML) 17 Å
CMA
Smectite 17 Å
Chlorite 14 Å
Illite 10 Å
Kaolinite 7 Å
Goethite
Hematite
5
S1
(n = 8)
8
4
0
2
75
11
0
4
S5-S3
(n = 38)
82
1
0
3
11
2
2
3
L03-L01
(n = 23)
29
13
8
15
18
3
15
2
L10-L05
(n = 22)
33
2
9
23
11
1
22
1
L12-L11
(n = 24)
1
13
15
36
22
1
13
overbank facies (levee and crevasse-splay sand-
stones) and (3) distal overbank and floodplain
mudrocks with beds of sandy to silty sheet-flood
deposits. The facies associations have been inter-
preted to represent different types of fluvial
channels based on sedimentological well core
data and lateral extension of sandstone bodies
inferred from well log correlation and seismic
mapping (Table 5). The great variability in vertical
and lateral facies distribution of fluvial channel
systems in general, coupled with the difficulties
in interpreting well cores and well logs in terms of
channel types and alluvial environments (Bridge,
1993; Miall, 1995, 2006, 2010; Weissmann
et al
.,
2011; Fielding
et al
. 2012; Horn
et al
., 2012), leads
to considerable uncertainty in the fluvial style
and sandstone body geometries inferred from the
present dataset. However, because of a lack of
outcrops of the late Triassic to Early Jurassic reser-
voir rocks in the Snorre Field (and other oil fields
in the northern North Sea), sedimentological data
obtained from well cores and electric logs were
used to construct reservoir models (Diesen
et al
.,
1995; Nystuen & Fält, 1995). The reservoir model
made from interpretation of fluvial style and sand-
stone geometry has been confirmed generally by
the production history of the Snorre Field since
1992.
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