Geoscience Reference
In-Depth Information
Exploration wells 2/4-12 and 2/8-15 were
drilled in areas characterised by strong negative
amplitude anomalies at the top of the Tor
Formation (Fig. 4). Neither well discovered hydro-
carbons, as the formation proved to be water-
saturated. Calibration of log data to seismic
sections (Figs 5, 6 and 7) indicates that the upper
channel-fill unit (red amplitude) has a higher
porosity than the lower unit (black amplitude) in
both wells (Table 1).
Detailed core descriptions and sedimentological
logs from wells located outside the channel were
also investigated (Figs 10 and 11). The condition
of the core material is extremely variable; older
cores, such as those from wells 2/4-12, 2/4-A8,
2/4-A-6, 2/7-4 and 2/7-14 are in poor condition
with numerous rubble intervals and extensive
sampling disturbance. The preservation of the core
material from more recent wells, such as 2/8-15, is
much better with fewer, shorter rubble intervals.
Core descriptions and biostratigraphic data in this
paper are in log depth. Cores are shifted to log
depth on the composite log figures and on the well
correlation panels.
Table 1.
Overview of the gamma ray, density and neutron
porosity values for the channel-ill facies association
in wells 2/4-12 and 2/8-15.
Lower
Channel Unit
Upper Channel Unit
Well
2/4-12
2/8-15
2/8-15
Average gamma
ray (API)
8
8
12
Density (g cm
-3
)
2.35
2.15
2.40
Neutron porosity
(fraction)
26
28
15
API = American Petroleum Institute units.
(A)
(B)
2-4-A8
MD
(m)
-0.15
Por.
Den.
2.95
0.45
Top
Tor Fm
Gamma Ray
API
Core
facies
Nanno
zones
MD
(m)
1.95
0
30
3225
Top Tor Fm
3230
3235
3240
3245
3250
3255
3260
3265
3270
Fig. 10.
Composite log of well 2/4-A8,
including (A) wireline logs, core
facies (legend in Fig. 8) and (B) related
sedimentological log. MD = measured
depth in m; Den = density log in g cm
-3
;
Por = neutron porosity in fraction.
API = American Petroleum Institute
units. Well location in Figs 1 and 4.
3275
3279.6
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