07/01/2021
REPORT OF
GEOPHYSICAL LOGGING
OF BOREHOLE AT
OGBEUKWU, NDONI,
ONELGA,RIVERS STATE
CONTRACTOR:
CLIENT:
STELINE NIG. LTD, 45 ABA ROAD,
PORT HARCOURT, RIVERS STATE
NIGER DELTA DEVELOPMENT
COMMISSION, PORT HARCOURT, RIVERS
STATE
JUSTUS OKEY
GEOPHYSICS CONSULTANT,
NDONI BOREHOLE LOGGING REPORT
GEOPHYSICAL LOG OF NDONI BOREHOLE
With the use of SASLOG 200 electric logging system, down-hole
electrical logging run of the borehole was carried out on the 7th
of January, 2021. Three parameters were measured and they include
Spontaneous Potential (SP mV), Long Normal Resistivity (LN 64”
Ωm) and Short Normal Resistivity (SN 16” Ωm).
The short spacing is useful in locating strata interface (but
more influenced by the drilling mud) while the long one provides
better information on the formation and the fluids in permeable
strata.
The procedure adopted involved lowering of the multi-electrode
probe manually to the bottom of the open hole at about 137m below
ground level while readings were then taken point by point at
intervals of 3m as the cable was pulled out of the hole.
Readings could not be taken at depths above 9m because it was the
mud level outside which the instrument cannot function.
The field readings are tabulated and represented graphically on
the attached sheets.
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NDONI BOREHOLE LOGGING REPORT
FIELD READINGS
COORDINATES: OGBEUKWU, NDONI, ONELGA, RIVERS STATE
Date: 7TH JANUARY, 2021
SPONTANEOUS
POTENTIAL
RESISTIVITY (Ωm)
SP (mV)
SHORT
CORRECTED
LONG
DEPTH CORRECTED
SN
LN
NORMAL
SHORT
NORMAL (m)
LONG
FACTOR FACTOR
(Ωm)
NORMAL
(Ωm)
NORMAL
(Ωm)
(Ωm)
0
0
0
20.2
121.9
67.7
0.00
0.00
0.00
0.65
0.78
1.28
0.00
0.00
0.00
3.28
3.93
6.43
0.00
0.00
0.00
0.58
0.84
2.28
0
3
6
9
12
15
110.2
56.2
116.7
56
113.4
53.1
105.9
54.9
118.5
67.8
127.5
156
111.6
58.6
108.8
49.2
118.7
49.7
97
49
99.9
53.4
102.7
51.8
96.4
8.60
7.86
5.50
5.96
5.52
6.54
6.16
7.24
8.18
8.12
8.16
9.53
10.43
4.21
5.19
4.30
6.68
5.51
3.45
4.72
3.78
5.80
4.88
4.99
5.05
43.17
39.46
27.61
29.92
27.71
32.83
30.92
36.34
41.06
40.76
40.96
47.84
52.36
21.12
26.04
21.57
33.52
27.67
17.30
23.69
18.96
29.12
24.48
25.05
25.34
9.60
8.26
6.80
6.96
6.52
7.54
7.16
7.25
8.28
9.21
8.16
9.78
10.15
3.06
3.04
4.07
3.41
3.32
4.20
4.45
3.76
3.77
4.71
2.07
2.25
18
21
24
27
30
33
36
39
42
45
48
51
54
57
60
63
66
69
72
75
78
81
84
87
90
2
0.00
0.00
0.00
11.95
17.24
46.67
5.02
20.47
Clay
196.51
169.08
139.20
142.47
133.46
Fine - medium
154.34
sand( partially
146.57 iron contaminated
148.41
aquifer)
169.49
188.53
167.04
200.20
207.77
62.64
62.30
83.41
69.74
67.98
Fine - medium
85.92
sand( severely
iron
contaminated
91.13
aquifer)
76.91
77.13
96.41
42.37
46.10
NDONI BOREHOLE LOGGING REPORT
48.1
102.3
50.9
95.2
39.7
52
20.2
68.6
25.9
68.4
32.3
69
35.1
78
33.5
4.07
4.11
5.13
4.06
5.08
3.95
4.55
3.87
3.18
3.18
3.20
3.19
3.20
3.19
3.21
20.42
20.61
25.76
20.40
25.51
19.84
22.86
19.44
15.96
15.98
16.08
16.01
16.04
16.01
16.09
2.32
2.39
2.47
2.41
2.31
2.10
3.29
3.49
3.49
2.55
2.70
2.77
1.78
1.77
1.77
3
93
96
99
102
105
108
111
114
117
120
123
126
129
132
135
47.41
49.01
50.64
49.39
47.27
43.03
67.31
71.42
71.34
52.16
55.21
56.76
36.48
36.19
36.29
NDONI BOREHOLE LOGGING REPORT
RESULT AND INTERPRETATION
The interpretation of resistivity log in a terrain like this is
often not too easy as a number of factors combine together to
influence the result obtained but with the knowledge of the
geology and experience/records of boreholes in the area, a fair
deduction can be made from the data obtained.
Using
the
‘Long
Normal’
values,
which
give
more
reliable
information on the formation, there seems to be a generally good
correlation between the electric log and the driller’s samples. A
profile of the depth penetrated by the probe shows zones of
comparatively lower resistivity values from the surface to about
15m
ranging
between
12Ωm
and
46 Ωm.
These
low
values
are
consistent with the occurrence of clay layers. The resistivity
values between 15m and 135m indicate the presence of sand layers.
However,
iron
resistivity
contamination
signatures,
with
is
clearly
the layers
delineated
between
from
the
15m and
54m
having a lesser degree of contamination.
The
SP
chart
is
largely
featureless
fluctuations in salinity.
4
since
there
are
no
NDONI BOREHOLE LOGGING REPORT
CONCLUSION AND RECOMMENDATION.
Based on the information mostly from the electric log, drill
cuttings,
and
a
review
of
the
geology
of
the
area,
it
is
concluded that the borehole has penetrated the predominantly
araenaceous Coastal Plain Sands Formation (which are generally
known to contain highly prolific aquifers)
In view of the conclusion made above with respect to the total
drilled depth, it is recommended that depths between 45m and 54m
are good for screen placement.
Gravel-pack material must however, be of texturally mature grains
(i.e. rounded) as those obtained from river-beds and must be
generously used to cover up to 15ft above the top of the screen.
The well must be developed immediately after casing installation
to avoid clogging of the screen slots by the clay from the
drilling mud.
.
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NDONI BOREHOLE LOGGING REPORT
DRILL CUTTING DESCRIPTION LOG OF NDONI BOREHOLE
DEPTH (m)
LITHOLOGY
DEPTH (m)
3 Clay
6 Clay
9
12
15
18
21
24
27
30
33
36
39
42
45
48
51
54
57
60
63
66
69
72
75
78
81
84
87
90
93
96
99
102
105
LITHOLOGY
108 Fine - medium sand
111 Fine - medium sand
Clay
Clay
Clay
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Medium sand
Medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
114
117
120
123
126
129
132
135
6
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
Fine - medium sand
NDONI BOREHOLE LOGGING REPORT
DOWN HOLE ELECTRICAL LOG CHARTS OF NDONI BOREHOLE
Signed:
Justus Okey (NMGS No: C-09-3960)
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